I got up this morning to find another had opened up to reveal a head about the same size or a little bigger so... decision made.
I had bought these on impulse at Home Depot and wound up with six plants in the ground. Which is about all I had room for anyway. I found the little info-stake. It says they're "White Cloud" and get six inch heads so I suppose this one was getting pretty close anyway.
Anyway... this one is gonna be lunch!
They seem to take a lot of space/time for a one head yield so will probably get replaced with... I suppose tomatoes since I started more than I have room for.
Thank you, your comments have all been helpful.