Springlawncare and seeding notes:
Can you put down grass seed now? Probably, but if it germinates and then we get a freeze it will likely die. If Spring seeding, I tend to put it out around the time of my average last frost date. For my zip code that's April 14th. Lot's of online websites will tell your your average last frost date. Most Spring seeding ends in grass not making it through summer. Your results may vary.
Unless you're willing to go through some very specific extra steps, you can't use pre-emergent herbicide and seed in the Spring. You can spray weeds prior to seeding, however most 3-way type herbicides (Weed-b-gone) says wait about 2 weeks after application before seeding. In practice, a few days is really all that's necessary, but you definitely want to wait to spray new grass until after you've mowed at least once and twice would be better.
Another tip is don't dethatch or core-aerate after applying pre-emergent herbicide. Disturbing the soil breaks the vapor barrier created by the herbicide and puts holes in your protection.
If you had heavy crabgrass last year, I recommend a spit application of dithiopyr as your pre-emergent if you plan to seed in the fall. If you don't plan to seed in Fall, a split app of any pre-emergent is fine Look at the label as it's one of the three most commonly used pre-emergents and will be listed right on the front of the bag. A split application in April and again mid June will give you better control, and dithiopry will wear off by September when you want to seed.
I almost never recommend weed'n Feed type products. Most homeowners don't apply them right and get sub-par results on the weed killing part of it. If you have lots of weeds, just buy a cheap hose end spray weed killer and douse the yard when the weeds really get rocking. Best time to kill weeds is when they are actively growing.