It sounds like you're in a solid position, and taking the time to stabilize before moving on to the next deal is a smart approach.

If I secure renters and show a lease agreement and deposit can I get into lower interest rate mortgage?

Quote from @Clayton Silva: 2nd position HELOCS on investment properties are typically capped at 70% LTV and have rates ranging from 9-11% just a heads up unless you use a local credit union where you have cash on deposit with them. 

Would it be a good idea to take a deposit to secure the deal until the rule clears?

Can your first payment be in 90 days, so you have time to rent the property?

Quote from @Kaushik Sarkar: Hi,I am looking to invest first time with a turnkey developer,  who is buying the land and building a multi unit commercial retail center and some apartments.

Quote from @Stacy Raskin: There are DSCR loan programs for first time investors. 

Specifically, the the loan guarantors need to have controlling ownership in at least (i) 3 multifamily properties [with the first acquired at least 2 years ago], or (ii) 1 multifamily property that has been owned for at least the last 5 years. 

My ideal time to have an appraisal complete is post renovation of the house, but BEFORE the tenant moves in.

It's gone through a bit of a fad-craze so I'd say first thing to look out for is vet'ing the credentials of them, there business.