Oohhhh, Nice Plant there Yann!
Good Growin'!
As far as pollen is concerned, I would recommend using what you can, as a small chance is better than no chance, and there are always exceptions to the rule. Besides these are plants we are dealing with, and predicting exactly how long pollen is viable is not an exact science.
I have done things over the years that wasn't recommended or "wouldn't work", only to discover that what people thought wasn't possible... is!
So using old pollen, cold pollen, or even ancient pollen is better than no pollen!
Also, one thing that people do know often works, is that if you need to slow down the flowering or extend the bloom time, is to keep the temps a bit at the lower end of the plants likes.
On the reverse, if you need to speed it up a bit, try keeping the plant a bit on the warm side. (Don't go to extremes, but we do this with other plants all the time, to speed up blooming, or else to slow down & extend bloom time.)
If dealing with old pollen, try taking a portion of it & re-hydrate it a bit with distilled water, or even other "things". Something at all is better than of just letting the flowers die away with no "romance" at all!
When you live long enough to see that new ways are always replacing the old, and new ideas, methods and procedures are always becoming the newest "right" way of doing things... then you realize that there are no real "definite", 'set in stone' ways of doing things. We won't know what is possible unless we are open to trying what shouldn't work.
There was a time when people didn't understand that VFT's & other temperate CP's needed dormancy & that it could be accomplished successfully even if you didn't live in their natural area. To think of growing them outdoors was looked at as foolish by many growers, but indeed this is now common place. Just as that the world in not in fact....flat!
I do hope you get a worthy mate for this nice plant.
Don't give up and be sure to keep posting for their "arranged marriage" until you get the right companion for it!
Good luck and keep us all posted on your results.
Paul
PS: Good to see you are still doing amazing things in the hobby!