I tend to look less at air temps and more at what the water itself is doing. If the pool water is hovering in the low-to-mid teens and climbing during the day, opening early usually works out fine. The cold nights slow things down, but they don’t really hurt anything as long as you’re not dealing with freezing conditions.
One thing that helps in shoulder season is keeping the cover on whenever you’re not actively working on the pool. It holds whatever heat you gain during the day and cuts down on debris, which makes those early weeks a lot less work. You can also start with shorter pump run times and adjust once you see how the water responds.
Opening early is mostly about management, not risk. If you’re okay checking in on it regularly while the weather sorts itself out, it’s usually easier than trying to rescue the pool after it’s been sitting closed through a few warm spells.