How long after using feed and weed can I reseed

I am new to gardening and it looks as though I have dropped my first clanger.
I intended to reseed some small bare patches in my new to me lawn before the cooler weather arrives.
I have been told that as I treated the lawn to a coating of Westland Feed Weed and Moss killer a week ago I should not reseed the lawn for a few weeks because the lawn seed would not germinate.
I wanted to get the lawn reseed this year but will it be to late in a few weeks.

Thanks

 

Good morning alan kearn ...welcome

I usually wait 3 or 4 weeks before reseeding however I am the impatient sort and I think a full 4 weeks is better.

Ideally weed n feed applied in August and then grass seed sown in early September.

So, I would sow seed before the end of September....both soil and air temperatures should be fine for it to germinate.

How big a lawn do you have? You could overseed next spring if germination is sparse