Lactation questions? Tmi

I'm 26 weeks pregnant and I have a few questions for lactating/breastfeeding moms! 
My nipples have gotten larger/longer but I'm still not lactating any is that normal. I have found a few dried spots on my boobs but I can't squeeze any milk out. When will I start lactating? Sorry if this Is tmi I'm just very curious. Will certain foods effect your lactation?