How long to the flower stage

All the seed stores say something like 50-60 days flowering time. But how long does it take to get to the flowering stage? Unless im being stupid and the 50-60 days is from seed to harvest but i dont think so. Im in UK if that makes a difference to growth, growing in greenhouse

are you about to plant out in a greenhouse ???????????? it takes as long as it takes to get plants to size you wanna flower them ???????????/ 50/60 days is just for flowering