A bucket of weeds in March will be worth several barrows of weeds in April or May. When few other plants seem to be growing the weeds will be making headway, so sensible gardeners will get at them now. In some places weedkiller or a good mulch will be useful but in flower gardens and places where more dense planting exists, weeding by hand will be the most practical approach.
Some gardeners scuffle and hoe, others prefer close contact using trowels or a hand fork, which allows much closer contact with soil and plants, and enables a greater intimacy with your charges.
It allows one to distinguish between wanted and unwanted weeds - not all are enemies - and it gives an essential close-up of the developing and emerging plant-life at ground level. The real gardeners will be down there on their knees. Others won't think about the small wild seedlings until May and then will wonder at being confronted by a threatening wilderness.