I'm 26 years old with a full time job and want to start investing on the side until I grow my portfolio and profIts enough to be able to Invest full time.

I believe we have a long way to go to catch up in terms of both student rental housing prices and student rent rates (some students are still paying $200/bedroom).For these reasons, I believe investors can make a bigger profit with less risk investing here in Windsor.  

You make your money when you buy, so you want to buy low enough to have enough margin to cover rehab plus your profit at the end.

With my W-2 income, I can still qualify for a 30-year fixed rate loan at 4.625% (a no-brainer in my opinion)2) I have capital that I need to deploy and the measly 3% interest I'm earning simply doesn't compare to how those funds could serve me in the rental market.

Simply being able to live for free, allowing you to purchase a 2nd home down the road makes this a good deal. 

And if you really want to exit that market to another hotter one, since you forced the appreciation, you can then evaluate if you are willing to sell the property at a discount (below market value but still good profit because of your forced appreciation) just to get into the hotter market quicker.

I mean....3-7 of those could eat up all your profits.

Should I wait to graduate and simply start off by house-hacking a few triplexes/quads and go from there, or should I start actively looking for deals to utilize my private lender and to get my foot in the door and start scaling as early as possible?

All she wants to do is to get some profit from her right. 

@Cherrell Thomas cash flow is the profit that's left after debt service, property taxes, property management, common utilities (if any), reserves for repairs (small things like leaky faucets, AC servicing, etc), and capital expenditures or capEx (larger things like a new roof,new HVAC, major plumbing overhaul...these are treated differently on taxes, written off over a specified longer period) and other expenses.The first item I mentioned, debt service, is where the answer to your question is.