Flag them so you can find them and dig want you want to separate in the fall.

Here is a link that might be useful: Propagating Perennials

Per the site below:
Most bulbs are best divided when their foliage has passed its prime,
I find late May or early June is when most of the foliage has yellowed and withered on most spring flowering bulbs in my zone...possibly a little earlier for crocus.

Sue

Here is a link that might be useful: Dividing Bulbs

You can divide them and immediately replant them. It is best to wait until the foliage has died back to insure that they will bloom the following year. Crocus multiply so rapidly in my yard that each year I find several clumps that need dividing. Some I replant immediately; some I wait until fall. Good luck with whichever method you decide to use.