Yeah mate, best way to do it is, if you know you're coming to a stop, unclip in plenty of time. I still give myself loads of time if I know I'm going to stop. We've all fallen - it's just the way it is haha.
Also, I'm sure you do this, but unclip to your strongest side, or whatever side you unclip to, always unclip to that side if possible. Then it just becomes second nature, and you don't think about doing it.
So for example, I'm right sided, so always unclip to my right side. I lean to my right and when I get started I'm always pushing off with my left. Similarly when I get on the bike, it's left foot in first.
I guess it works differently for everyone and obviously in emergencies, unclip to whichever side you need, but it's definitely better to get into a habit of unclipping to one side so you don't have to think it through beforehand.
Took my mate out on a ride last week and he loved it, so we went again on Thursday. His second ride in, and he gets hit by a bloody car! Totally this woman's fault, she pulled out of a junction despite it being a straight road, high visibility. My mate wasn't going fast as he was still getting used to it, but he went into the side of her passenger door. Somehow come away with nothing but a sore back and a grazed elbow. Bike's survived too - her car was in the worse state but serves her right.
Been thinking this a lot, but in driving tests and things, they should definitely be making learners (not that this woman was a learner, you could just tell she was one of those hesitant, nervous drivers) aware that a lot of cyclists wear cleats. It's so difficult if cars stop abruptly, or stop-start - especially on hills. You get used to it, but if the drivers aren't aware (which unless they cycle, they probably won't be) then it can get a bit scary.