Answered by Shaykh Faraz Rabbani
Is it permissible to perform two rakah of salat-e-istikhara after the witr and before sleeping or we have to finish this before witr.
Walaikum assalam wa rahmatullah,
It is permitted to pray after witr, though it is optimal when possible to pray witr last. (For details: see answer below).
As such, it is permitted to pray istikhara after witr.