my rule is water once then no water until leaves are about 5 inches, then water weekly unless it is cool.

If your cutting is well rooted, and when it's growing strongly with lots of leaves - usually in late June, July and August, they can take quite a bit of water. In dormancy and in Spring just as they leaf out, there is a much higher risk of overwatering with rot being the end result.

Don't know where you live so that will influence everything. I also don't know if you are growing in ground or in pots.

I grow all mine in pots so, during growing season, I water when soil feels dry about a 1/2" to an 1" down. We also have high humidity, so we probably don't need to water near as often as someone in say, Phoenix, AZ.

Thanks for the responses!

I'm in the Pacific Northwest USA and I have her in a pot. I'm still bringing her inside at night and on our wet days, which have been many even up to a few days ago. The highest temp we've had so far is barely 85F.

I dont think you will have to give it any additional water in the Pacific Northwest. I water my rooted plumerias once a day (they are big plants in small pots so they dry out completely every day in the warm weather). I try not to water my cuttings, but if its above 90F and very very sunny, I will give them a little water too.
My plumerias in the ground never get any additional water (actually I really dont water any of my tropicals in the ground too often).
-Alex