Might be worth seeing if you can find out ahead of time -- online perhaps, or over the phone -- how full (or not) the earlier flight is. If it's already overbooked by the day before you travel, then going so early is prolly a waste of time. Otherwise, it's worth a try, as far as I can see. (I have had it happen before, myself, but it was 20-ish years ago, and so many things have changed since then...)