Hi Jacobus,
  You didn't say whether you planted in soil or germinated the seeds in between paper towels or coffee filters... With the coffee filter method, I'd plant as soon as you see radicles poking out. If you planted the seeds in soil, let them get at least one set of true leaves fully out and handle the seedlings very gently by the cotyledons only when transplanting.
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Diluted seaweed extract is a very gentle fertilizer, so it can be used immediately after transplanting, but when the seedlings are small the amount of nutes they can take in is limited, so I shouldn't think you'd need to water it in more than once every 1-2 weeks.