When a felon gets out I want him to come to my school I have a trucking school how long does it take for a grant get processed can I get it done while they are in jail

There is no such grant.

First to be qualified for a grant, your school must qualify as an approved school. So have you qualified to receive government fund?

Next there are no grants for felons unless it is local grants or loans though non profits.

You can of course give them loans, or allow them free education to help them,

All those 'grants for felons' ads you see online are scams.
There are some education programs. See the Education Connection.

If you are wealthy YOU can offer them grants from your own assets, or offer free or reduced cost training. But as others have pointed out. Conviction of a felony is not a shortcut to get free things at the expense of taxpayers.

What state are you in? Your research starts with becoming affiliated with a state approved program that works with felons. Every state has one so start with your own department of corrections to see if you meet state requirements. Also, grants for felons are dispersed through faith based organizations, private foundations, and non profit organization.

http://mygrantadvisor.com/assistance-for-ex-felons/

I can already tell you if you have no credible job placement service in place you can forget it.