HSA start date

If someone wants to use an HSA as a retirement fund but they dont have the money to invest it one yet, could they at least start one with a minimal payment of like $100. And then from that point on start collecting their medical bills to use in retirement?

Like year 1 they put in $100, year 2-5 put in $0, year 6+ they max out. Then in retirement they want to start pulling out money and they have a $3k medical bill from year 2, would that be allowed?

So basically, if you want to use an HSA as a retirement account is it beneficial to open one asap, bc that is the date you can start collecting your medical bills?