I am in zone 6

Just wondering if I can now use reg lawn food or when I can 4 weeks after i used Scotts Haltz

I'll skip the lecture and admonishment. You can apply up to a pound of fertilizer per month (avoid late June through mid-August if using non-organic fertilizers) with little chance of damaging the grass plants.

Im sorry for sounding so stupid about these things but you said a pound ? what does mean in relation to my hard it is 10,000 sg feet is it 1 pound per 1000 sq feet?
Greg

I was referring to one pound of nitrogen per one thousand square feet of lawn. Fertilizers usually containing substantial amounts of fillers and may contain other nutrients like potasium, phosphorous, iron or in the case or Haltz, herbicides. So a pound of product may only contain 1/5 of a pound of say nitrogen. The numbers on the bag (20-10-10, 39-0-5, etc.) indicate the percentage of total bag weight of each of the nutrients: nitrogen, phosphorous and potasium. A 50 lb bag labled 10-10-10 will contain 10% of each of the nutrients or 5 lbs of each. Therefor, if you want to apply 1 lb of nitrogen to each one thousand sq ft of lawn, that bag would cover 5000 sq ft of lawn total.
Most bags will state recommended spreader settings to be employed for applying the product. That is what I recommend you follow. ESPECIALLY for anything that contains a herbicide.
As you are a bit of a novice, if you really feel the need for another fertilizer aplication, try Milorganite. A 50 lb bag of 5-0-2 contains 2.5 lb of nitrogen and 1 lb of potasium (and 4% iron). Spreading it over 2500 sq ft will apply one lb of nitrogen per 1000 sq ft. So for 10,000 sq ft of lawn you will need 4 bags.
The best thing about Milorganite is that it will do great things for your lawn once temps are high enough and most importantly, if you screw up by putting too much down, the likelyhood of harm is small. That way you have leeway in learning what setting you need on the speader to get the 4 bags to cover your lawn evenly.

I re-read my original post. It was pathetic. You aren't stupid and I shouldn't presume your experience level. I'd be happy to clarify any other questions you have that are in my wheelhouse.

I just bought 4 bags of Milorganate I will apply it tonight thanks for the tip

Everyone has a bad day, yt1.

You can apply Milorganite or other organic fertilizers at any rate, any time of year, or even every weekend, without fear of hurting anything. You can apply the same day as you apply chemical fertilizers if you want. But I would not apply chemical fertilizers with temps running above 85 degrees. Between heat and dry soil, adding salty chemical fertilizers can be too much.