To water or not to water Monnierara Millennium Magic?
 

I got this orchid a month and a half ago and the new growth has tripled in size I'd say, but I read everywhere to wait until roots are 3-5 inches to start watering but the ones I can see are not growing and are not nearly as long.

I only lightly watered it once since I got it because the old growth was very shriveled.

Should I start watering it or should I wait longer?

https://i.imgur.com/B3WeKuS.jpg
https://i.imgur.com/sYZPulF.jpg

When I can't see what Catasetinae are doing root-wise, I wait until I see a second flush of roots starting at the base of the new growth. When those show up, it's probably ready. Soon...

Actually I think I can see the sheath bulging, I think roots are coming. Thanks!

If the temperature is not too low ---- for example, estimating 25 degrees Celcius or higher, then watering won't have any bad effects on any of the roots. But just the usual recommendation ------- avoid waterlogging media such as sphagnum ----- which is to avoid potential root drowning.

In Dominican Republic temperature won't be an issue.
I suggest you start watering, but make sure it doesn't get into the crown of the new growth.

I don't think temperature is an issue even in places like where I live... my Catasetinae are in a nice, warm greenhouse during their dormancy and as they start to emerge from it. One still has to respect their dormancy needs. The cycle of Catasetinae isn't driven by temperature as much as by rainfall in habitat. They tend to come from habitats with pronounced dry seasons. I don't see a need for a rush to water, once that second flush of roots shows up, it's definitely waking up.