Some people grow 3 plantings, with 2 weeks between sowings. Or you can plant all at same time, but with varieties with different maturity dates. I grow melons next to my early corn planting so the vines can ramble in there after the corn harvest.

I grow 7 plantings with about 10 days between.

I suggest a good rotation time for melons...melons tend to have more sicknesses than anything else I know.

And no, I don't plant a second planting in the same place, but rather I plant a cover crop following the first 6 plantings.