I'm with the folks who think the firing will be closer to the assumption of power. Castellini & Co. have been involved in baseball for a while. They have wanted to run their own team and now have the ability to run their hometown team. I can't imagine these guys will be mousy when it comes to instituting their vision. I'm guessing Castellini & Co have a type of GM in mind, if not a specific candidate to take over the team. You don't participate in various ownership groups, raise so much money, and wait months to take over your hometown team without having a firm idea about what you want and don't want in a GM. Plus, it's not like the current GM has done a great job or has a long term remaining on his contract. The meeting with Pinella tells me these guys can't wait to get in place and start playing with their new team. For better or for worse, I expect a lot of action out of the gate.
They won't do it their first day because they won't want the firing to detract from their day and the announcement. I'll give them a few days to assess things (put in air quotes) and fire O'Brien on January 25th.