It's never too late ( well about 7 to 10 days they start to assign rooms) to make a request or a change.
Then when you get there if anything else is available they will switch you if you request that then.
For our June trip we had a 1st fl near a DSA as our request. The room wasn't ready so we asked wjat was . They had a 5th fl and a backside 3rd fl avail. The CM told us to hold off if we could as our room was great location. We did and it was .