Onset of ringing can be hours, days, weeks, months, or even YEARS after the noise exposure.
Sudden loud noises often cause tinnitus within hours to weeks, and occasionally, if the loud noise didn't cause quite as much damage, potentially a few months.
I had a bad cold June last year. Then July last year I shot a cap gun and an hour later my left ear started to feel a little warm. Then during the next day I noticed a reactive "humming" sound that would get louder if someone on the phone spoke to me and my own voice would do it too. Then that night I get a high pitched ring I'd say between 5 and 6 kHz. It was mild and didn't worry me too much and after a few days it faded into the background so I would have to put a pillow up to my left ear to hear it but the odd thing was that sound coming into my right ear would slightly increase the volume of the tinnitus in my left ear. Strange. For a few days I got some mild distortion in high frequencies and then a reactive hiss/ring that went away after 2 weeks.
I am unsure what actually caused the sudden episode of louder ringing that started in my left ear this January but I effectively killed that ringing with a single very high dose of Prednisolone. There was a couple of months right after that where external sound would cause it to spike but nowhere near where it was at its loudest. The spike always lasted a few seconds, then went away.
Now that spike doesn't happen nearly as loud, but I noticed since around late February that I would get a soft "zing" or "ting" sound when I heard any sounds that fell into that range where the "zing" would be - it would also repeat if the sound in that range was continuous so it would go "Zing ting ting ting zing ting ting" and then stop as soon as the external sound stopped. It bothers me sometimes but I don't let it worry me since my guess is that is hyperacusis and will go away eventually or at least to a point where it won't annoy me. I have had a couple of times where it went away for a 3 days or so then came back. I suspect it will go away but you can't put a timeline on stuff like this.
Where my sudden loud January tinnitus onset was caused by a virus or something other than the noise exposure is unclear and it is possible that this could have been the case - but this tinnitus was very close to the pitch/characteristic of the tinnitus that I had always had in the background after the tinnitus I had experienced after the cap gun incident. All the same tone and characteristics...
So my guess is noise induced hearing loss can absolutely cause delayed onset tinnitus and yes it can occur in only one ear - my guess is it is only logical that the ear that takes the brunt of the acoustic trauma would be the one that starts ringing.
But I am still unclear if there were other causes. I have had problems with both ears since 2020 and left ear since 2016 that were relatively mild but still...