Even if you have the loan they don’t have to be back on until the end. I would confirm this before running with it but that is my understanding. Of course once you have the loan it makes sense to have them on full salary since it will all be forgiven. And you can only spend up to 25% of the forgiven portion of the loan on non-payroll eligible expenses (like rent, utilities, etc) so you need to make sure you have enough staff back on to spend at least 75% on them.

Lots of good info at the Cain Watters blog and on their webinars: