According to the charts in
https://www.coindesk.com/price/ as of this time, price has been fluctuating slowly for the Bitcoin after the fork.
Is it time for Bitcoin holders to sell or hold on to their coins? Or to
move and invest to the newly found Bitcoin Cash?
Last sentence doesn't make a sense at all,move and invest to the newly coin ?
An Altcoin always be like that and will never replace Bitcoin,it's a logic and everybody understand it(although some people did not),
lets take a simple example,when everybody hyping about it and many people buying Bitcoin to get Bitcoin Cash[BCC/BCH] for free.
A large exchanger named 'CoinBase' made a statements that they won't support it,and they explained it because BCC/BCH had a problem in their network and to keep their investor safe from it,they decided to not support it.
So,more likely nobody will move all of their money into a newly reborn altcoin.
And for Bitcoin,of course it's not to late to buy and it'll be a bad decision for you if you sell it now.
because another 'BIG PLAY' will happen soon.