IF you have a bb getting fitted, than you already have a crank ? otherwise you wouldn't normal fit a BB without knowong the type of cranks.
So use your current crank, take of the rings and fit a single ring (for single ring setup, i.e. non-ramped or profiled) and use that for now.
You may need a different crank bolts or use some spacers (or fit a bash ring or grind an old ring down to act as one. Many options.
