Is there any chance of an early hard fork or SegWit Implementation ? Risks ?

So, I've been hearing a lot of fuzz from investors that are scared of an early hard fork or an early SegWit implementation. The reason they're scared is because they currently hold their bitcoin in an exchange.

So my questions are:

1) Is it possible that a hard fork comes early ? Why would it be ? As far as I'm concerned here is how it works: The miners signal the BIP they're willing to adopt and at the date the BIP is supposed to be implemented they implement it. Can they implement it early ? isn't it hard coded ? Or am I missing something here ?

2) What are the risks associated ? from what I heard if you do not own the private keys of your wallet the blockchain might be hard forked and you won't have access to your "doubled" funds. Is that accurate ?

Thanks