Bittrex are ready for Jade
The Crown masternode and systemnode network is about 80% upgraded.
Nodes which have not updated by block 2,327,000 (about 2 hours from the time of this article) will be disconnected from the network by their upgraded peers. The network will switch from PoW to PoS consensus 3000 blocks later (at approximately 15:13 UTC on 12 April 2019).
Bittrex have updated their wallet and publicised their readiness for the switchover in the following article. Deposits and withdrawals are suspended until the switchover completes satisfactorily but trading remains enabled.