I started these dragon fruits from seed and I’ve never pruned. I want them to flower how should I go about it? (Dallas,Tx)

What are those little tendrils on the dragon fruit? When will they fruit? I have bamboo sticks I want to tie them to but I’m not sure where to prune. I have them outside by a tree late winter to early winter. I also only use rainwater on them.

I read it takes 2-3 years for them to produce fruit from seed should I expect them to fruit this year if I prune them? Sorry for all the questions.