Harvested 3 of the centre frames today so 24 days from when they were first put on. I pulled the frames to have a look before harvesting, centre 4 frames were all full and capped outside frames full but only 50% capped so decided to just harvest the centre frames and give them some more room to work with.
Interestingly one of those harvested was the frame that was removed when I moved a conventional frame up from below to entice the bees into the flow frames so has only been on for 17 days.
Took about 5min after starting to extract for bees to start tearing at the wax and salvaging what was left in cells.
Edit: Not the best pic, taken with my phone but interesting regardless