I believe the verbiage actually says 24 months, and yes, that's a hard requirement (there are a couple other means of going direct SRO, but not for navy). I have known one person to get a waiver, but he had a MS in Nuclear Engineering, and probably some other awesome stuff on his resume. If you apply with exactly 24 months as EWS, there is a good chance that you'll get passed over.
That being said, starting as an NLO is a lot easier. There's a DSRO in my crew who started at the same time as me and has to do almost everything I have to do to qualify as an NLO (minus 9 of the 10 watches at each station) but only has a year to do it, as opposed to me having 26 months. Plus the opportunity for time and a half and double time pay is pretty nice.