depends entirely on the strain and growing conditions. I have a few animal cookies x god bud, very slow to start strain, my night temps have been in the low 50s, and i was low on perlite, so it took me about 3 weeks to get there. However in these conditions my dutch Kush and Pineapple purple skunk clones will add 4-5 nodes at absolute minimum in the same amount of time. as well as a lot of undergrowth. I have had F1 strains from seed like my Special Queen x Afghani at their 4th node and topped in a week flat though. Lots of variable come to play in this