Personally I’d house hack it all day long to build up that portfolio.

You can build up goodwill sending grocery cards at Christmas, having a mini fridge to rush over the moment there is a problem, giving rent credits, etc. and it will mean LESS THAN ZERO as soon as you have a late fee you expect them to pay, a pet that you cannot approve, anytime the rent goes up, telling them they can't paint the walls and ceiling the color they want... then you are the scumbag landlord.

I’m wondering if anyone has advice on how to get started or if I should wait and keep the money in the stock market and diversify to other  investments to build up more cash.

If so, then you are either losing your water in your tub's p-trap or there is slime build up in the shower drains and/or overflow. 

Consider starting with a traditional rental property or house hacking first to build up your investment capital.

We can build up to 11 more units, or we can have mobile homes on the site.I like the idea of having a Tiny home community whereby I lease the parcels per mobile home model, build Tiny homes on a trailer frame and sell them with owner financing, with a clause that they cannot leave the site unless they are paid off.

It’s also a good idea to build up your cash reserves, as lenders may ask for evidence of cash reserves to tide you over for 6 months or more.

I’m young and want to build up my number of investment doors in the most efficient way possible and with the lowest downpayment’s possible.

Repeat this process and you can easily build up a portfolio. 

Take that same concept and apply it to your work, source deals, wholesale to build up cash and once you find those golden nuggets you can take those to get lenders and keep for yourself.