Kill weeds prior to sowing vegetables?

I have just bought Gallup Blograde 360 which I am going to use to kill off all the grass and weeds that have grown on my vegetable patch over the winter. I am not sure that I have bought the correct product and if so I can always return it to the shop and exchange it for something else. I intend to kill the weeds and then rotovate the ground before starting to plant my vegetables for this year. How long would I need to leave it after spraying and before I rotovate it. Also how long after spraying do I leave it before planting vegetables. I would appreciate it if you could let me know if I have bought the correct product as I am wondering if The Irish Organic Weedkiller would be better. I do not want to do anything that will affect my vegetables later in the season. Thanks