How long can the city wait to send you a speeding camera ticket?

In 5 years of driving, I've gotten one speeding ticket. In the past 3 weeks, I've gotten 6. That's not a typo. The ticket that was the most immediately reported was mailed to me literally two months after it happened.

After I've gotten the first of these 6 tickets, I haven't been caught speeding once. I feel like this is just ambushing me with a bunch of tickets that are purposely reported as late as possible so they can catch me speeding as many times as they can. It seems a little unfair.

If they had reported the first ticket I had gotten within like a week or two, I'm going to be extra careful on the road to avoid any more. But now I've gotten six tickets for a total of $450.

So does anyone know how long (I live in Cedar Rapids Iowa) the city can wait to report a speeding camera ticket? I've read on places on the internet, and the answers range from 2 weeks, to 30-60 days, to 6 months. Can anyone give me a clear answer? I would like to fight these tickets If I can.