Trigger shot question help!

D • 29. Married. TTC #1 since Feb.2018

Hi!

Do they give you a precise time you have to take ovidrel shot??

I just finished CD 7 on leterzole . They said I would take the shot either March 13 or 14, but will confirm on the 13th

Totally forgot I have an exam on the 14th at 8am which will take two hours! Will this affect the shot and timing of it?

Sorry first medicated IUI so I’m unsure