I set my campaign in the 2050s, so that I can slowly introduce the cool events of Shadowrun, like the Bugs and Renraku shutdown etc. At first I tracked time, starting in the Winter of 2050s, but then realised that with downtime etc, the team was quickly moving into the future.
Now I fudge time. Its still "2050"ish, but when? is a question we never explore. Its always raining in Seattle, though every now and then is snows. But actual calendar time never really moves forward until it suits the story for it to move forward. One day, one day sooon, it wil be 2051. But only when we're ready.
From a mechanics point of view, the team still pays for lifestyle etc during downtime between missions.
Hope this helps.