A Galio game is most times decided by his late game ability. This means that while Galio can mess up really bad ,and possibly lose a botlane encounter, if he were to get tanky enough into late game that he can hold 3-4 people of the enemy team without dying quickly he can secure a possible 2-3 kills and have a push back on the 4th and 5th. So starting into your early game you need to make sure that the carry you are with has a play style. Watch how they react to moments and see how they engage. When you solve this mid-game will be the time you need to, based on carries movements, jump in and hopefully secure a few kills every now and then for the carry you will depend on later.