Loan Options - Primary Residence vs. Investment Property rules

[Thomas Cuddihy]

Hi, all! My name is Thomas and I am at the VERY beginning of my real estate investing journey. Bigger Pockets has helped my confidence to get started, so I'm very excited to be here. 

I currently reside in Montgomery County, Maryland, which is a fairly expensive market to buy/sell real estate in. I was having a conversation with a friend who invests in real estate, and I told him my concerns about having enough cash for a investment property. 15%-20% down to secure traditional financing is a lot of dough, but my friend suggested that I apply for a loan as a primary resident, and then rent it out anyway. I feel like that's a "too good to be true" scenario, but I'm not sure if that's something folks here have done before.

So there's my question: is it possible to apply for a loan as the primary resident, and then rent out the property? Is there a time limit before I can do that? Or, better yet, am I thinking about this all wrong? 

 Any help is much appreciated-- thank you, all!