Proper way to update a nodeTree

Hello there !
I’m trying to update a nodeTree because I try to access some nodes’ witdth and they don’t even have the time to have a size ^^

Something like :
context.space_data.edit_tree.update()

Thanks !
Seb

Or maybe just a way to let the code breathe a little bit, in order to let the nodeTree set up as it should.
With a coroutine or something ?