How long before I can apply weed & feed to a new seeded Kikuyu lawn as I have weeds coming up.

We recommend to wait at least 3 months before applying any herbicides, including Yates Weed 'N' Feed products. Best thing to do is hand removal of weeds and apply a fertiliser such as Yates Dynamic Lifter Liquid Concentrate. This will help the help lawn establish and out-compete weeds.