Depends on how much you've got to do and how urgently you want to do them by and how long it will be before AS is ready for general use (weeks more likely than months*). If you've never used GC, then even starting now would be useful in the sense of getting you used to the concepts about how/what to record your census sources. Also everything should be compatible between GC and AS since it's all done in Gedcom and has to work with Family Historian so you won't need to re-enter work done in GC. And since it's free you've not lost anything except time.
* I haven't got a clue!