When to add pk 13/14

Hiya people, a quik question..

When would I add pk 13/14 to the nutes :confused: Am in the 2nd week of buddin and didnt want to miss out on anything if i can help it.

Am using a hydro NFT techique..

thanks.. :dance:

peace :stoned:

use pk in the third week of flower for a full week good luck m8