I would leave everything alone, if you move the nest, I have tried, only to find the hen where SHE wanted to be, and the nest where I WANTED her to be full of cold, dead eggs.
I do hover, and start checking on day 20, I know they say 21 days, but.... however, I let her do it the way she wants, I just give the whole floor a grooming out several days before, put in fresh bedding. After they hatch, mine have always taken the chicks down, they jump that small distance with no problem, and gets them a drink and creates a new nest on the floor of the coop.
Really do not interfere too much, if you listen carefully you should hear peeping, a good sign, but don't try and peak, that just can upset the hen, and sometimes that will ruin things, it is so hard, but just leave them be.
At about 3 weeks, I will place a wide board up near my roosts, and my broody hens will get the chicks up there by week 4.
Hope it goes well, if it doesn't, get some day old chicks, and stick them under her. Nothing is more fun to watch than a hen and chicks.
Mrs K