I'd wait, unless you are totally blown away by an offer. Catchers get hurt and there will be contending teams that want to add a catcher who can hit come the trade deadline. Desperate/contending teams are more likely to part with a little more in the hopes it gets them over the hump. Right now everyone is headed into spring training healthy and optimistic so nobody is ready to part with their young talent. Let's see what we can get for him in July. Heck, tell him you'll deal him in July. Maybe it'll provide him with some incentive to play well. It's not going to matter to the Brewers results, but will make him more valuable on the trade market if he's having a monster year.