As far as I know, fliuentassertions contains no equivalent to NUnit's DelayedConstraints which allows to specifiy that a condition should be satisfied after a certain wait time.
I am using an overload of ActionAssertions.NotThrow which takes additional waitTime and pollingInterval parameters to achieve a similar effect. That is, it repeatedly executes the Action every pollingInterval milliseconds, catching any exceptions, until the Action either stops throwing exceptions or the waitTime has passed. In the latter case, it fails with an exception.

I was wondering if there is some interest to include this functionality in fluentassertions?