Okay, here is my take having been a lender for the last 25 years.
His stated goal is to get to a point where he has enough cash flowing properties that throws off $4000.00 a month in cashflow. Presuming, so he can quit his job and go full time into real estate. He has between $50K - $100k he can put into this to get it off the ground. That said, this will not be an over night type thing, rather this will take a few years to get to the point where it could do this?
My best advice is that you will need at least $300K to put into this to get enough cash flowing properties to throw off $4000.00 per month. How do you take your nest egg and grow it enough to be at $300K. Well you flip properties. The average flip in my area is getting $45K to $100K in profit, not counting taxes. You would need to do 4 to 7 flips to have enough after tax profit to get your nest egg to 300K.
Once you have done these flips, you then will buy 11 single family properties that you will use the BRRRR method to buy low, rehab, rent, refinance and repeat. if you are cash flowing $363.00 per door, which you should easily do after your rehab, then you will finally have your $4000.00 in cash flow.
So in the end, how long will it take you to buy, rehab & flip the 1st 4 to 7 and then additionally, how long to buy, rehab, rent, refinance and repeat then next 11 properties? I know professional flippers that can do that in as little as 2 years. However newbies, it could take 5-6 years. I would set out a conservative time frame and then methodically take the steps to get there.
You might want to partner with an experience flipper for the first 1 or 2. Use their knowledge to fast track your learning curve. Be careful who you choose, it could go bad, at which point you would have to rebuild from a bad spot.
I would also seriously consider getting your realtor license. This will help in all aspects of this journey.
I hope this helps?