Synthetic saddles should not need a "break in" period, only leather saddles do (as far as I know). My local bike shop used that as a sales pitch to discourage buying a Brooks (which they didn't have in stock) and instead buy a synthetic saddle that needs no break in period (which they did have in stock).

My bike shop has a saddle fitting system to choose a saddle of appropriate width for your backside. It might be something worth trying out if your bike shop has it. I was too tempted by all of the positive things I read here on the internet about Brooks, so I ignored my local bike shop advice and mail ordered a Brooks B-17 (what I'm using now). The Brooks is comfortable, but I think there are a lot of other comfortable options out there.