Confused about blooming size

[Maru777]

Hello,

I finally have a question that is thankfully not a problem But I am pretty confused about this - blooming size. I know most sellers will say blooming size or not yet blooming size but what does this even mean in relation to the full size of the plant. The reason why I am asking is because in my last shopping spree in January I bought some seedlings. No idea how long they will take to bloom and don’t really mind the wait as they are cute to see growing. But now one of them seems to be putting out a flower spike. This thing is smaller than my hand! Its full size is nowhere near what it is now as these seem to grow much bigger (phal bellina). On the other hand, I have some dendrobiums that have been growing like weeds but even though they are now close to 80% of the size they will be, they don’t feel like blooming yet. And another den that is blooming instead of growing. This is so confusing. Is there a rule of thumb that can tell one roughly how far away in time a flower is? Or is there a 50% of full size = blooming size equation? I’m sure it will differ by type of orchid too but in general? I added a picture with the little one that got me thinking. Pretty sure that’s a flower spike, next to the root - it’s been growing those too