I would advise withdrawing all of your coins stored on Nitro ASAP. There is a fork coming tomorrow. It's a segwit2x fork to make transactions faster and cheaper and will probably be pretty popular.
I can tell you from bitter experience that they will delay a withdrawal request for about 24 hours if a fork snapshot is coming. I would not wait if you want your segwit2x btc coins.
The resulting coin is already trading north of $1,000.
https://coinmarketcap.com/currencies/segwit2x/
These are futures, the snapshot has not been taken yet so of course no coins have been issued. Also, it appears the developers of B2X plan to not issue the B2X that is associated with Satoshi's known address ("he" has huge holdings) and will instead issue those coins to B2X users.
Nitro will not give you these coins and will try and delay your withdrawal as well.