Question
I have a large bare area within an older existing lawn because a playset/swingset was removed.  There was no grass there before, so I have filled the area with top soil.  I am concerned however with matching the existing plane of grass as the new area sits in the middle of existing lawn. Obviously, as the new soil settles it will sink.  Do I now need to roll the area to tamp it down.  How long should I wait before seeding the area?

Answer
I would allow the soil to self-settle a season or two before worrying about getting a perfect grade on this real estate.  Rake smooth, Seed, then Roll AFTER Seeding to achieve optimal Seed-to-Soil contact.  (It's also important, and especially if you are growing this Lawn in Warm Season Grass country, that the Grass variety you select match your existing Lawn.  But we'll cross that bridge only if you want us to.)

Your new Lawn patch will be mowed once it's up and running.  Unless you have a visible DIP in the Lawn, your Lawnmower is going to cut a smooth swath from left to right.  If you've missed a bump or dip, Lawnmower Burn will ruin this Green Swath effect -- that's what you call it when your uneven Soil directs the Mower Blades down, gauging into the Grass like an ice cream scoop at the soda fountain.  Not a pretty sight.  You can hear the Grass screaming as it happens.

Next Summer, if that seems to be happening after your Lawn is established, correct it by topdressing the dip(s) with a thin layer of Sand mixed with Humus or Compost, a little every week; you'll find the old Grass will grow through it fairly quickly.  Just don't layer it on too thick.  1/4 to 1/2 inch is all you should put down.  And that's only if you need to.  Odds are, you'll do it perfectly the first time, and when you're done, it will be like the swingset was never there.