From what I understand of how Irish moss works, it needs to be boiled with the wort in order to be fully effective. If you want to try using gelatin to clear your beer you could do that after fermentation finishes up. Otherwise you could just let it slide and it won't have a negative effect on the taste, it just might not be as clear as it would be with the Irish moss. I've never used Irish moss myself, and as long as let my beers sit long enough before bottling and refrigerate them long enough before drinking they are pretty clear.