Hi all. I keep reading that I should install the baseboard after the floor and then use shoe molding to hide the gap. But I don't see "how" to install the baseboard as there will be a gap wider than the baseboard. How does the baseboard rest on the floor while installing without falling into the gap? I haven't started the floor yet so I'm just speculating about a problem that may not really exist.

Usually if the base is long enough, like 16' footers some of it will rest on the floor as you fasten it. Or you can measure the distance and mark it if your so inclined. I never have that problem because I would rather undercut the drywall if I need extra expansion space than use shoe or quarter round.