If you need the diapers TOMORROW, velcro will do until you can get some aplix to replace it... it's a bit of a waste of money and extra work to take it off to put the aplix on, but it'll get you by. You will need to put aplix on them eventually though because velcro will NOT last at all.. it will wear out very quickly so unless you want to replace your velcro once every few weeks, you'll need aplix eventually.
But if I recall, you're still pregnant, right? What I would do personally (and what I did do) is as long as you are not making pocket diapers (not prefold pockets but fitted pockets), or putting fancy tabs on the wings, is you can sew the whole rest of the diaper and just sew on the aplix when it arrives in the mail, which won't be TOO long

My diapershop orders usually arrive in about a week if it's a small order.
If you can't do that according to your pattern, I would tough it out and wait. I know it's hard

But you don't want to put velcro on a diaper in a way that you'll have to take apart the whole thing if (when) you have to replace it.
Hang in there - I know how hard it is to resist until you can start! I feel ya!