I'm not sure Preserve actually *does* anything, honestly. Yes, it makes the orb white, but I'm not entirely certain it makes the synth behave appropriately. Fulfillment and Maker's Muse seem to be equally useful for standard spamming.

As far as when to use them, I hate using abilities when the orb is blinking, unless it's an ability that will let me keep going despite the instability. So, for Maker's Muse and Fulfillment, I'd usually wait until the orb is a solid color. For Preserve, well. . . like I said, I don't trust it, so I'd probably save it until I've had to wait a few times, or something.