Nutrients were started at 0.5 ml/litre as soon as first leaves developed gradually increasing by 0.5ml per week until I hit 25ml/litre. I seem to to get great fast starts with this with seedlings rapidly developing over a matter of days and within 2-3 weeks of popping I usually have 3-4 sets of leaves.
Germination tip: I put the seeds into damp kitchen roll in a saucer or similar and cover with clingfilm to stop drying. In a dark drawer these can take days and days to sprout but recently I have been placing the saucer on a sunlit window sill for an hour or so where they can warm up and get some natural energy from the sun. This seems to trigger a strong sprouting response within the next 24 hrs. It works for me everytime for me and tends to encourage them to all pop at once as opposed to some taking days longer.