Start feeding nutes at 1/4 strength at 4-5 nodes. But this depends on the soil you are using... If the soil has nutrients in it already (like Miracle Grow), you might not need nutes for 2+ weeks, depending on many things. What kind of soil are you using? Does it have the N-P-K values listed?

That 18-18-21 sounds quite strong :wtf: I'd look into getting Canna or Foxfarm nutrients... Veg, bloom, and PK+ at least. And don't mix and match manufacturers, stick to one. They have very clear feeding instructions online, just google "foxfarm feeding schedule" and download the pdf.

Good luck:jointsmile: