Slit seeding

 I am getting ready to rent a slit seeder and do some over seeding.  Am I too
early ?  I live in western MD. around Hagerstown.

 
Yes, it's early.  Seeds need soil temps in the 50s to germinate.  You
won't be there for about a month or so.

If you seed now, the seed will lay dormant until it gets warm enough.
The problem is, to get decent germination and establishment, you need
to keep it constantly moist.  I'd rather wait until you know the soil
is warm enough, then seed, apply starter fertilizer and start watering
and keep it constantly damp.