Neem has a pretty high chance of burning the pistils, which can stunt the flowers’ development, reduce your yield, and provide vectors for botrytis (bud rot). If it were me, I’d explore other options first.

Here on the farm, we use green lacewing larva with great success - they get right to work on eating up the aphids. If you don’t see any aphids on your plants but still want a preventative measure, assassin bug eggs are pretty cheap and should hatch within a week of receiving them.

If you’re in the US or Canada, I can recommend a great retailer for the assassin bug eggs if you’d like. And if you’re in the PNW I can also recommend one for the lacewing larva as well. Otherwise, your local grow store should hopefully know of a distributor.