I am able to tell when a semp starts growing a bloom stalk, but are there anything's to look before before the bloom stalk starts to grow?

The center of the rosette will start to cone, sort of rising higher and higher. Wish I had a pic or two but I only have pics of when I lop off the cone before it develops to a bloom stalk so that maybe new offsets will appear.

Color also intensifies a bit on a rosette that's about to bloom, but the upward habit of the leaves is also a tell that can be noticed shortly before the cone begins to develop. Rosettes that are about to bloom also have a tendency to "sit up" a little, in other words their center of gravity appears to shift from the soil line to the center of the plant.
As early in the season as last week I start checking rosettes for these features, hedging my bets as to which will pop a bloom.