Its up to you. I am Planting in soon like yourself, and have planned to plant out in final positions, then intercrop with some pf the salads, radishes, lettuce, etc.
This helps with ground cover and thus keeps weeds down. by july/august I will leave the leeks on their own, there tops should have developed enough to keep bed fairly free.
I also give them a drop of liquid manure, to help them after the salads have reduce the available nutrients in the soil.