For where you and I live John, I would wait until Autumn, it’s always nice and damp then, you know how dry the ground can get through the summer, it’s so free draining.
John , we’re all like that when we start off, so many people, every year think they will sow early, get ahead with planting etc, you learn over the years. Plenty to do over the summer. If I have a packet of mixed seeds, I sow them in a tray then sort them out when they’ve germinated. Does it say what the seeds are.? There may be some annuals in there.