I run a similar build, though the game is usually over by the time I purchase Aegis. A main difference though is my starting item(s) and the replacement of the Heal summoner spell.

First, I choose Clairvoyance over Heal's early game bait advantage (it doesn't scale well in to late game in my opinion) so that I can track the enemy jungler, cv (clairvoyance) between the bottom (or top) brushes to see in to both for a (always) free facecheck(s). I ward the map frequently since I am the support and take 0 farm, but the cv def helps to secure the major objectives on the map, or just cv'ing top/mid so if they don't have wards up of their own early they are still somewhat safe.

For starting items; I like to go a single Fairy Charm, 2 Green wards, 3 hp pots, and a mana pot. With my heal and 3 hp pots, I never wish I had taken a Regrowth Pendent over early wards and more pots for more active hp (or trading hp pots for mana instead if I think their will be more harass to spam Q)

A suggestion; as support, red and blue buffs should be going to your AP and AD carries respectively after your jungler has taken them early game, so you have very little use for 2 points in buff increase mastery (I am assuming that you know the buff increase mastery does not increase baron buff duration).

Just a few suggestions, but overall a +1 from me.