For newborns, I find we get the best success rates when sessions start at 10.30 or 11am.
This is because your baby won’t tend to sleep all that well at night (which seems like poor planning for everyone involved!), so they’re at their sleepiest during the morning. Sessions that start later can result in your baby being more wakeful, although of course it isn’t an exact science.
The latest session start time I’ll take for a newborn is 1.30pm. After this point, we’re edging towards the ‘witching hour’, which traditionally gets very poor results for a photo shoot.