It's for that reason that WaitNNN and Find functions are best for looking for objects for which there is a delay... you can set the delay timers within those functions to something bug (like 60000 ms) which should cover a wide range of timing problems. If the object returns sooner, the function will return sooner.
Additionally, using WaitNNN and Find functions are actually recommended when doing any "Exists" test. The reason being is that, if the object is not found and does not exist, those functions return an empty stub object with Exists = false.
Anywho, hopefully you get it figured out. Let us know if you need any further help.