Around 1 Gallon per Month of Growth/Flowering.... so 4 wks veg as you have done is sufficient in 1 Gallon Pot.....potting on should occur around now and at least 10-14 days prior to flowering to enable sufficient root development prior to entering flowering.
Looking good...I think the Nitrogen Deficiency or Lockout will remedy itself after re-potting into some Rich Organic Soil and entering into flower
(Sometimes I get some l Nutrient lockout which displays similarly to yours if I over-water when transplanting into larger pots
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