It depends if you are planning on planting a seedling, clone or repotting.
Seedlings need very little food, so you can get away with what's left after the flush and then continue as normal after the 1st 2 to 3 weeks.
Clones/repotted plants will need a bit more food more quickly being a bigger plant, but can still get away without much food as they stretch their legs.
If you can get hold of some compost, that is great to top dress and add life and minerals.