Posted: 22/04/2016 at 21:37
The biggest problem with new lawns is with the soil settling unevenly. This results in humps and hollows. Sometimes this is caused by organic matter ( manure or tree roots etc. ) rotting and creating holes into which the turf falls. This shouldn't be an issue with your lawn. The other problem is the soil not being firmed evenly before laying the turf.
I would recommend treading firmly and evenly, with your weight on your heels, all over the area and then rake level. This should knock out any clods of soil and fill any hollows. Take your time and get this right. Once the turf is down, you will never be able to get under it again.
One last thought, is there any chance of the backfill soil in your new drains settling down any more? if so, then I would probably leave the turfing until it has rained a few times to see how the land settles.