I started at 2 wks by putting him on his tummy on my chest for 30 secs. Then build up to aft every diaper change. By 2 months baby cld hold his head up stably without bobbing and started flipping frm bck to tummy and vice versa at 2.5 months.
after 2 weeks while giving massage and then slowly increased frequency & duration every couple weeks.
3 weeks plus