Time frame to refinance

[Steven May]

Looking to purchase my first home in the next few months. 2-3 bedroom single family house unless I can find a duplex that I could qualify for. Going to use FHA as I plan to either live-in flip, air bnb, or house hack to live for free as I will be working as a night shift nurse in the KC, MO area.

Wondering, what is a good time frame is to wait to refinance so that I could possibly move the FHA to a conventional so that I could scale up and then move into another home with a new FHA and utilize the initial home as a rental?

Also, approximately how much equity do you need to have to get a Home Equity Loan? Or is it just a percentage of whatever you have already say 75% of however much of the loan is left or that is paid.

All advice welcomed. Thanks!