actually does anyone know how important it is to check in during the first few minutes or hour? are most of the good spots gone in the first 1-2 hours or something?
Always depends. I just went from Chicago MDW to Denver (always sold out flights). First one I checked in within minutes of when I was allowed to, and got B14. Returning I forgot to check in the day before, so checked in morning of (maybe ~10 hours ahead of flight) and got B37.
It's also worth noting that you don't HAVE to print your bording pass when you check in. You can check in on your phone or PC and not print, then go to the kiosk in the airport and get your boarding pass which will have the same number you already checked in at. Some people don't realize this, so I thought I'd mention it.
In my case early bird check in would have only been 10 bucks. Not exactly a high cost to guarantee a good seat on a popular flight, but budgets differ. Would have been nice to have that extra room in the emergency exit rows...