Is this a different saddle, or just a same-model replacement. If the latter...zero time. If the former...I usually give it a couple of weeks. If it hasn't felt right by then...it isn't going to. Time to try yet another model.

I've been relatively lucky with saddles, at least since about '89 or '90 whenenver it was the Flite came out. Before the flite I think I used a Rolls, and maybe Regal...but usually just what came on whatever bike I bought. Once the Flite came out I used it religiously on every bike until the SLR came out...maybe 12-13 years...since then its been SLR for me. I've tried the Aspide Tri and the Arione Tri. While comfortable, all the extra padding did for me was give me saddle sores...I was disappointed because they really were a bit more comfortable for aero riding over about 80 miles...but I couldn't put up with the saddle sores...so I'm back to the SLR.