Normally your seedlings shouldn't need feeding for about two to three weeks after they sprout.
Start out with the diluted dose and give them more as they seem to need it. If you start feeding at 1/4 strength and they take it well, but seem to want more, then start giving them more.
Recently I started my seedlings on a diluted dose, but they were behaving like they wanted more, so I gave them another diluted dose the next watering. After two feedings in a row I still wasn't satisfied that they were getting enough, so I fed them a third time in a row, and this time I gave them the full recommended dose.
I'm using Fox Farm liquid fertilizers at the moment, and I find that these FF liquid fertilizers can sometimes be used at full strength from the very first feeding.
When feeding some people wait for signs of nutrient deficiencies before fertilizing. If you feed your plants and you notice a little nutrient burn, then your plants have enough fertilizer for the time being and you need to lay off them for awhile.