Create a task that executes after a specific time frame

Hello I am trying to create an AHK script which will have a task of constantly left clicking for a few hours at different intervals. I have this already programmed so it pops at 300 milliseconds then 299, then 280, then 301 etc… for about 5 minutes and restarts.After let’s say 5 hours I want to be able to hit esc and the up arrow and then enter on the keyboard. How would I build this? I imagine this task would go before the repetitive task I’ve created. Any suggestions would be appreciated.