You can (probably shouldn't yet depending on your level of frost) do any type of thatching now, but wait on your premergent weed product until May. Grub products should go out around July.

This is still early for thatching IMO, as there's still a lot of frost in the ground (at least in downeast there is). Working frozen/semi frozen turf can and will shear off your roots at the frost line when the top inch or so is soft. Then you're negating anything you do.

Any and all seeding and aeration NEED to be done before you get your premergent down, as seed won't establish in the early weeks after pre-em. Aeration creates passages for weeds to grow through the "blanket" that pre-em creates.

Be careful following what the landscapers do, as some are looking to do pre-em early so they get to come around and charge you to attempt to kill 7 tiller crabgrass with the pea shooter arsenal they have.