My plants are mostly indica and they're all +...

Hello there, looks like we're both growing NL and other indica dominant strains. So when to flip? If you'd like to fully utilize the space and max out your plants as far as possible (upwards) I would not allow them to surpass 60cm in height. This will allow for roughly 60% stretch and leave you with the recommended 18-24 inch buffer space required for your lamp for appropriate core light spread. In my experience, so far, my Indies don't surpass 50% stretch, BUT if you're concerned or feel they will stretch further (trust your gut, my friend) you can play it safe and flip at 45cm. This will give lots of buffer room and you won't have to worry about over stretching or light burn. (I'm also assuming your pot is about 30cm high as well and that has been taken into consideration for these measurements). Just quickly and personally. I'm flipping at the 60cm-75cm mark because I feel it won't surpass the 50% stretch (with these specific girls). But that's my gut telling me that👍😉. Hoped this helped my friend. If you choose this as the answer, there is no need to 'select' it. Of this is the info you needed, there's no strings attached. If you have more questions about flushing and nutrient schedule changes, pm me anytime. Cheers my friend.