ahead of time:

Before the deadline(from Collins Dict) 就是说比最後期限要早一点点,可以用於表达完成得及时的意思.eg:Tony finished his essays ahead of time.

ahead of one's time:

having ideas or attitudes that are too advanced to be acceptable in the present.有很超前但很难别人接受的想法 eg:Sue's grandmother was ahead of her time in wanting to study medicine.

ahead of schedule:

与第一个意思相似..(我认为可以互用) eg:Tony finished his essays ahead of schedule.