I thought it was more complex, that you had to remove the stamens of the ones you wanted to pollinate so they wouldn't self fertilize. No?
If I save the pollen from the earlier blooming plants I could still just do as you said?
As far as I know, that's how pollination works for most flowering plants including cacti. You don't have to remove any of the sexual organs to induce fruit formation. It's only with certain plants such as some Orchids where you might have to remove the stamens in order to produce seeds, but not in cacti. However, it might be easier to just break off the stamens and store them as they are larger and easier to work with than just raw pollen.
And yes, I believe you can store pollen. Pollen is just a protein, so you'd store it in the same manner as other proteins in order to keep the pollen active:
Cold and dry. The method i've seen is to collect the pollen and brush it off into a small plastic baggie and then place it in a freezer. Be sure to label things, though.