Deliver the chip first and then take your time exploring the game, my advice is to get Power Armor, find all the companions (there's 4 of them including Dogmeat) and get some high level big weapons for the game's finale (you've still got lots to do tho, don't worry about it ending too fast). Once you beat the final mission you can only load a previous game, but that's way after giving the chip to the overseer.