Weedy top soil

I got a bulk bag of top soil for some grass seed and now the new grass area is full of weeds, it must have come with the top soil as these are different weeds to what we have normal. I've read that you do not feed & weed new grass for 6 months....any ideas guys how to get rid of weeds without damage to new grass?

 

Many of the weeds will not survive the mowing. Those that do you will just have to deal with once the grass is established with a lawn weedkiller. Remember that grass is a weed and will fight for its own space.