The "all in" combo should be 3 autos, E , reposition to get a Q in and dodge any counter, W R auto auto. This is pretty easy to pull off with this build, no need for timing much, by th etime W hits rift and cosmic will be procced.

You have 2 options for heavy poke,
1. Auto, wait for rift and cosmic, Q-W-E
2. E a minion near the enemy - Q - W- get the PTA proc

For poke you wont get punished for,
1. E a minion near enemy - W - run away
2. Q enemy, if you hit Them Drop a W

Early game:
i usually go tear first with a control ward. I'm an agressive laner and we have Pressence and taste of blood. You can farm under tower pretty easily and as long as you save a stun for the enemy you should be ok. focus on farming and keeping th enemy from getting free cs. every time they step up, show pressure. Dont always use the same combo. Brand has options, use them. By level 6 you should be able to get the blasting wand and booties. Preferbly youd have a kill or two as well. Sometimes i go all in as soon as i get my ult and put out my ult and my E, dodge any counter they have like sion Q or irellia stun, and flash if needed. Once i feel i can stand still for a sec i Stun them with Q, Drop W(its guarenteed if you stun them and drop it imidietly) and auto for the PTA proc and Kill. if they arent dead already. the massive AOE from the passive Proc and w and e usually clear out the enemy minion wave giving me an advantage, or evening the playing field at the least. After that i usually pretend to push the wave, then go all the way back to my tower. this usually causes the enemy jungle to waste their time looking in bushes or just pathing to my lane at all when they could be farming.

MID GAME:
Mid game you should have 2 items, tier 2 booties, and the components for a third at the least. preferably youve farmed enough kills and lane minions to have 3 items and booties. At this point you are a kill threat to anyone with less than 3k hp. Your dueling ability is fairly high if you went nashors rift intso cosmic. You have amazing kite if you left ghost in, omnivamp keeps you alive as if your were a tank support, but of course your brand, you do brand things, and brand things include MURDER. LOTS OF IT. now you can get fancy. same combos as before but now you can split kill! Auto a support or mid laner 5 times and they are almost dead, throw your E - Q - W on someone else and they are almost dead. Now press R and everyone just kinda dies. If any survive you now have riftmaker passive, cosmic passive, ghost, and autos that hurt alot. Who can run?

Late Game:
late game doesnt happen to often for me. We usually either get an early win, or my team FFs. im almost always highest damage though. even in games im perma shoved into turret i make it work. the few games i have that went late was basicly this, play it slow. you arent omnipotent anymore. you have insane 1v1 potential, but if a sneaky yasuo waits for you to use your stun then tornado ults you, your probably dead. This build takes a couple secs to get off all your damage. So positioning is key. if your alive, the whole enemy team has to watch what you do, and they will. that alone give your team a massive advantage. By now your adc should be strong enough to 100-0 someone even if they were behind. if you dont see the enemy who can end you before you get off your combo play safe. if that enemy gets stunned or caught splitpushing, go nuts. Try to focus supports and tanks. they often have an adc or jungle near them and the damage will hit those targets making the team fight go in your favor everytime.
Dont get CC'd. you take too long to get off all your damage, if you get lux stunned you know someone is gonna throw themselves on you and choke you out. Cant fit a Q past a fat chogath if hes 1ft away from your face and your ult will only bounce between you and him so all your damage is being soaked up by the tank, rendering you useless.

ALTERNATIVE ITEMS:
If you end up against a CC heavy team, or a very mobile top laner you can swap everfrost for riftmaker. The loss in omnivamp is worth the ability to still kite even if you miss your Q. Also you can swap shadow flame or demonic in for arch angels if you have some of those champs who get away too often. with demonic id sugjest keeping riftmaker in though. No sustain at all mid and late game means you basicly have to give up lanes or turrets to a 2v1. With this much sustain and resistances you can comfortably sit under tower and keep atackers off your tower and farm at the same time. Early game can steam roll you so much on this champ and build id recomend picking boots against your laner and enemy jungle. Then if you need to later on swap them out last. Maybe your against a big boi like sion who is hitting his q and slows on you. then id go swities or tenacity booties early to make sure im winning lane. I may swap them for bezerker booties or ionians later.
Get greedy. Your damage is great, and you can hit half of your all in from the grave if you time it right. Your Q-W-R all still do damage if you get them off right before you die. ive killed quite a few people from the grave after being backlined by a kayne or fiddlesticks. Your scaling is awsome, steal kills if your doing well. going bot and getting 2 kills there doesnt screw your bot lane. Now they can free farm and get tower. thats more gold than if they had split the kills and assist. and likely they couldnt have gotten the kills if you werent there in teh first place. the only person who gets screwed is you if you go all the way to bot lane and only get two measly assist. You lose out on the farm in your lane, and the time it takes to go back there. 3 waves = 1 kill, and a turret is worth more than a kill. know what your giving up before you roam. remember your an imobile, you cant dash walls, and you dont have have any MS abilities.
Take care of your Jungle. This build lets you survive alot of engagments fairly healthy. after a gank, ask for help pushing the lane, this should regen some of your health, grab a health plant and help the jungle gank mid or bot. even if you dont succeed, it applies pressure to the enemy if they dont see you on the map. take the long way back to lane if you have time. ward your side of the jungle, get a pink ward in their tri bush or your river bush. the extra time you out of vision make the mid laner and top laner start playing passivly, maybe holding on to certain spells incase you pop up with your jungle. this can cause them to miss cs, slows their lane push, and can make them make stupid mistake liek backing early with bad wave control. Brand on a top island is a waste of a brand. brand needs to do brand things. like MURDER.
ENJOY! this build is alot of fun. so satisfying to proc PTA and your passive.