I am new to investing and I plan to make my debut as a real estate investor with a house hack in a multifamily duplex, triplex or quadplex. I currently have a full time W2 as a pricing analyst and I make decent income. I anticipate on getting a FHA loan to secure financing.

My question is should I use all the money that I can get pre-approved for or use a formula using expected cashflow along with my income to determine what my buying limit should be?