When to use "bloom booster" fertilizer?

I've been curious about this for a while, maybe some of you can straighten
me out?

I have some Dyna-Gro "Bloom" plant food 3-12-6. I was told that this would
help my flowers grow bigger & last longer. Is this true?

What I am most curious about is when to switch from regular fertilizer to
the "Bloom". Should I do it when a spike starts, when a spike matures or
when buds appear? Also, is there any chance that this stuff will help induce
a non-spiking orchid to grow spikes?

Thanks for you time, this group is wonderful!

-Jay