Using House Hacking BUT up till how far

[Karan More]

Hey Guys,

So here is my situation:
In 2020, I took a townhouse at very low interest rate as my 1st primary home. At that time I was new to real estate and paid 20% down payment for this one. 
After learning about real estate house hacking, I got idea of buying another SFH nearby by taking out HELOC and then rent out my townhouse.
But my agent told that, its best to get a duplex or triplex as new property and then later after 6-8months buy a SFH using house hacking. Because if I buy a SFH and then go for another using house hacking, I wont get lender to lend me money for my deal.
I don't want to try hard money route right now. 

My questions are:
Is that the best case for me? to go for duplex or triplex and then go for SFH.
After this, can I still house hack? Planning to do at most 4-5 so can have good cash flow.