i am planning on visiting a escort to lose my virginity. will 1 hour be enough to get it off 2 times ?

If you're a virgin an hour would probably be enough to get off a dozen times if you have the stamina. Newbies don't tend to last very long. 

Maybe 5 minutes is enough?

Don't be surprised if your escort lays there like a dead fish. Escorts are not sex therapists. My advise to you is to go to a legal US brothel and have your first time via a paid professional as opposed to an "escort" that loves nothing more than to rip off 'first timers.' Escort services care mostly about repeat business, and LOVE to rip off naive men who do not possess the social skills to get laid on their own. I'm surprised they even took you as a client because they usually limit their clientele to married men (easier to blackmail if they get out of hand). 

If she's an "escort", why are YOU going to visit HER? How does that qualify as her escorting you anywhere?

Depends on you physically. Most escorts get a hefty bonus for a second pop. Many won't participate in a second try.

One minute will probably be plenty of time.

More than enough time. You'll probably pop your load in the lift on the way up to her apartment.