...and there you were worrying if you'd be too slow, why were you ever worried about it Well done!
The good thing about starting off at 30+ is you have a sensible target to go for. If you'd done 29:59 then 24:59 is quite a challenge, whereas 29:59 from 34:xx isn't a doddle, but is reasonably achievable with a bit of application/practice.
The slowest person at our parkrun takes about 50mins, she jogs most of the way - I know that to those of us who have sub 30 times this sounds very slow, but if you see her finish you understand that she's giving it everything and we're quite happy for her to take that time.
If she was strolling round chatting and not putting any effort in it would be unfair on the volunteers who'd be hanging round (in the cold) to wait for her, but as it is she's more knackered than the 16 min lads.
If you can do 17min 2.5k you'll be fine; many parkrun courses are multiple laps, if you aren't up to doing 5k to start with you can just do 1 or 2 laps to start with (but don't cross the finish line please!) and build up.