breastfeeding while pregnant

Megan
Just got my BFP today and am still breastfeeding my toddler. She will be two years old next month. My question is, if you were breast-feeding when you became pregnant again, when did you notice you were supply dropping or drying up? My daughter is a boob addict and we are starting to night wean this weekend, but I want to lessen the blow for her by gradually weaning her during the day.