But I suspect they do have some sense of before and after, just not in linear time. It’s possible they have another dimension of continuity that isn’t time. They give the impression of never having encountered such concepts before, hence they have been in a state of not knowing about them at some point.
The solids/corporeals thing now makes me wonder about an alternate version of DS9 where the Founders are also non-temporal extradimensional beings (not the pagh-wraiths, I weirdly dislike that whole concept) whose response to encountering corporeals was to enslave them all. Encountering non-enslaved corporeals and non-temporals who disagree with them - or maybe were/will be them* - would be what kicks off the Dominion War. But what we got is really good too, taking one of Odo’s personal plot points and running with it was pretty cool (if expensive for the SFX budget).
*”We are, we were, we will be the lloigor.”