Buying Bitcoin now is the best time, specially if you are expecting a hard fork and split chain. The reason is that you just doubled your Bitcoin, one in Bitcoin Core chain and the other one to Bitcoin unlimited chain. There is no reason to dump and fear the hardfork. If ever it drops its price, new people will join in the community making the price to recover and eventually breaking the ATH.
Everyone says that even if you manage to get bitcoin in two chains, its cost will be very low. This frightens off many people. And this frightens me, too, because I do not want to lose my savings
And this is what the whales want, frighten people and make the weaker hand sell their holdings at the very low price. If you believe in Bitcoin, even if it split (Bitcoin Core coins and Bitcoin Unlimited coins) one of them will be the real Bitcoins and will start to go up once it is established. Then your will realized that there is nothing to fear because you have your coins on both chain. How you deal with it is up to you, but it would be better to wait before you decide on which one to sell first.