Outside of a Tillandsia vasectomy I've never heard of any treatment to prevent bloomage. Sometimes when the plants have been subject to too much pampering and coddling they can be resistant to flower. Maybe try to over-mother them a bit and when you're ready stress 'em out.

Joel, we had a discussion of this topic a few years ago (see link below). I don't think we ever came up with a definitive solution, but it may give you some things to think about. The same priciples should apply to Tillandsias as Neos and other genera.

If your primary goal is synchronizing bloom for pollination purposes, however, it might be easier to simply store the pollen of one parent in the fridge (or the freezer if it's going to be longer than a month or two) until the other one blooms. We've had a number of threads on that topic too. You can use the forum search engine to pull them up.

Here is a link that might be useful: Preventing bloom