How long do I have to charge my iPhone 11 for the first time

There are no special charging times associated with "first time" use of an iPhone. Use it as you would any other phone. Charge it when you are running low on power. Don't let it discharge to zero.

Here is some additional charging advice: When to charge your iPhone or iPad - Apple Community

As long and as often as your like.

You already got the right advice, not surprisingly. :-). But if you want to know more, check out this thread and the excellent User Tip authored by Lawrence Finch.

-- JDee