You could start it today, it only takes about 5 minutes...
Not everyone is on Facebook, including me. I'm offering stuff cheap to the membership for a week before closing down to remodel/rearrange the tanks and halting all sales other than John's foods.
So with nothing to sell, there's no reason to start my FB page beforehand.
...you can control who posts on your page.
That sure as hell will be refreshing!!!