If trigger is BEFORE I guess trigger will run before the check constraint.
But what is the order if trigger is AFTER? Does the check run first?
Don't guess, know Create Trigger:
The trigger can be specified to fire before the operation is attempted on a row (before constraints are checked and the INSERT, UPDATE, or DELETE is attempted); or after the operation has completed (after constraints are checked and the INSERT, UPDATE, or DELETE has completed); ...
beforetriggers -> non-deffered constraints ->aftertriggers (if constraints passed)