Ready for what? Transplanting into larger containers for growing on indoors or planting outside?

Outside - waaaayyy too early, in my zone mid-May if the weather forecast permits, in your zone it's going to be late May/early June before you can tranplant annuals outside.

Larger containers: As soon as the seedling develops a set of true leaves (not the seed leaves - cotedlyons - I know I butchered that spelling) you can transplant into a larger container. Always handle the seedling by the leaves, never the stem - if you break a leaf, no big deal, but if you break the stem it's a goner.