Mature enough to get pollen?

No. They will swell up, start going a bit pale then a white/cream line will appear on them and this is just before they open to shed pollen. You can wait until there are long stems of multiple male flower clusters and when the largest look that they are about to open, snip the entire cluster off and hang them inside a paper bag, they will then "after ripen", open up and drop their pollen inside the bag, making collection easy. If you only get a small amount of pollen, it can be cut 30-70 with corn starch then painted on very young female calyxes with a paint brush and you will still get perfect pollination as it only needs one pollen grain to fertilize the (seed) egg. Seeds will then take 4-5 weeks to grow and fully mature after pollination. A few young buds with all white pistils pollinated in this way will give you 100s of seeds.