I have the same problem. But from what ive heard, start last 3-4 weeks of cycle and continue throughout PCT.
If you cannot retrieve another bottle, maybe best to save it for PCT only?
If you only have one bottle it would be best to use in PCT IMO. Its definitely great to use on cycle to prevent shutdown, but only covering 4 weeks out of ten isn't going to do the trick.
Hell yeah it can certainly help with libido man, HCGenerate has a nice combination of proven ingredients that are geared towards doing just that. There's a reason it's always going out of stock.
I just got two more bottles in yesterday.