Young kids usually do best at sunrise. They are fresher and have not had any mishaps or skipped naps. It's always tougher on the parents who strain to look good that early but worth it for the smiles. You have your whole day ahead of you, and you're not stressing to schedule everyone, so they are in a good mood later that day.
Bring a surprise juice box and bust it outright when they start to meltdown. Especially if they never get juice at home, this is a big treat, and it's nice to take a break halfway through the shoot and get sugar in their system. They tend to go an extra 20 minutes!
Sometimes it's better to plan the photoshoot around the child's sleeping schedule instead of the light. I usually like to photograph at sunrise or an hour and 1.5 before sunset. These times vary throughout the year. If you know your child gets grumpy at the ideal time, let your photographer know, and we can work around that. Maybe more photos in the maritime forest on the way to the beach or in a nearby park with shade.
Leave the M&M's and goldfish at home. Promise them after the photo shoot and not during. When they have a ziplock bag of treats nearby, they tend to focus on that or even want to hold the bag and panic if it appears and then disappears.
I always bring a ball or noisemaker with me to engage children. This works well because it is a totally new toy for them to focus on and I hold and toss the ball near the lens. Another trick is singing songs or asking about animal noises. If your child is a "Baby Shark" fan let us know and we will break out into song for a smile.
