Hello Michael Duncan,
Assuming you have all your legal ducks in a row…
this still depends on many things:
what you want to take away,
the area’s economy,
how many students are signed up,
how many drop ins to allow,
will drop ins try to get free sessions,
how many trainers are working,
There is really no such thing as non working hours, either.
Do you have a business plan? You may do better to talk to a business manager who will be able to help you figure out all the details.
Add up all your projected costs and what you want to earn.
Be upfront with the building owner about all activity; do not keep anything hidden; be flexible, yet firm on your bottom line.
Good luck with this opportunity.