A little on the small side for 50 days old. I lost a couple weeks when I transplanted them from 1 gallon pots into 3 gallon pots, I was not paying attention and overwatered for a week, had all kinds of leaf discoloration issues, thought I was going to lose them but I managed to correct this, I stopped watering and slowly they bounced back. I trimmed all the damaged leaves. Good lesson to learn actually. Going to let them fill out the tent before flipping to flower so at least another week, maybe two weeks.
Once you flip these to flower, watch out! The growth is very rapid and pronounced. You will love it. And that smell is straight up heavenly when they start to really focus on bud development verse vegetative and root growth. From your pics they look rather healthy but I'm not very experienced. I will say that both strands I've grown from Humboldt Seed Co were very resilient despite me stressing them out a LOT. Good for noobs like me haha.