It's usually best if you use a "complete" nutrient i.e. one with DAP, but also the micro nutrients etc, like FermaidK or Fermax or similar. They look like an off white, or tan coloured powder. Whereas DAP usually appears as white crystals.
It's also common to mix them i.e. work out what the dosage is for the size of batch, then make it 40% DAP and 60% "complete" nutrient. This would then be split in 2. The first part being added once the "lag phase" has finished (that's when you've pitched the yeast, and after a while you see some airlock activity). You'd then give it a stir once or twice a day, testing the gravity after stirring, because you'd have to add the second half at the 1/3rd sugar break e.g. start gravity of 1.100, so the 1/3rd break is at 1.066 - that'd normally be the point where you give it it's last stir/aeration, add the second part of the nutrient/DAP/etc etc to the test sample (that's just told you that it's at the 1/3rd break), mix it into solution and then it's all added back into the batch, swirled to mix it in, then airlocking the batch and allowing it to finish...
regards
fatbloke