The stretch lasts as long as it lasts. Every plant is different. When I was in your spot, I used a ruler and checked growth every day until it stops. Let the plant tell you when.. I can't stress that enough. Let the plant grow..
This is my current grow.. The 1st pick is dark 25.. And start of preflower.. 2nd pic is today. Exactly two weeks later.. Day 39. Still on veg feed until flowers form, and the vertical growth stops.. Then I'll start bloom nutes.
Day 25
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Today- Day 39
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this is what the start of flower looks like..
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You got a couple weeks still. Be the turtle, not the hare.. Its not a race brotha! Let the plant tell YOU when, not you telling the plant when..trust me.. I learned the hard way.