Even after I start flying again I will have plenty of time to persue (and close) real estate deals. .

I have considered this, but due to Denver being such an expensive market to get started in my current plan is to keep buying using personal loans to secure the property for less money down.

@Sam SandTo answer your question direct: Legally only 14 states requires licensing to make a business loan, so odds are you can get started where you live.

I've been an agent for 3 years now and I've closed two deals, but want to start using my license more, so I'd love to hear how other agents got their business rolling!

In the last 2 months I've had to start the eviction process on one of my S8 tenants.

Start by reading the Ultimate Real Estate Investing Guide: https://www.biggerpockets.com/guides/ultimate-real-estate-investing-guide/introduction2.

When should I start the mortgage preapproval process for our upleg?

It would be at 75% LTV with rates as of today starting at 6.3%. 

When starting, I say "borrow as much as you can for as long as you can."

Start by reading the Ultimate Real Estate Investing Guide: https://www.biggerpockets.com/guides/ultimate-real-estate-investing-guide/introduction2.