My milk came in at 36 weeks/ colostrum at 27. Everyone is different. I'm almost 29 weeks now and haven't had any signs of lactating. Nipple stimulation helps, look up some ideas for smoothies and teas to help boost your hormones for breastfeeding. Nipple stimulating will give your colostrum a jump start/ if your body is ready. If not, just go with the flow and it will come eventually. My breast swelled overnight 2 days before I was induced, they were ridiculously full.

DO NOT I repeat DO NOT worry about your supply. You'll first make the colostrum. Then milk will come. Your supply will regulate around week 6-8 postpartum. If you pump before you're regulated you may cause an over supply which is not what you want.

when your baby comes you produce colostrum (even before) and that's enough and then your milk should be in a couple days after birth

Your milk comes in 3-5 days AFTER BIRTH. before that you'll make colostrum which is a smaller amount all that baby needs and it's packed full of antibodies and nutrition.

Just keep nursing and pumping. It'll come in.