Right from the start help your child to understand the need to obey, even if it means at times using an open hand applied to a sensitive part of his little anatomy. Obedience can be a real protection from all sorts of dangers. To children the whole world is something new and wonderful to explore, but such explorations can be fraught with danger. Obedience will be your newcomer's protection.
At a very early age, between one and two years, children can be taught to sit quietly for periods of time. If yours is a family that enjoys studying the Bible with others in a group, this will be very important to you. Children like to have books the same as Mom and Dad, and a little cardboard book with appropriate pictures pasted inside will often suffice at the start when pages easily get torn.
If your child becomes restless, it may be helpful to take a brief walk outside for some fresh air. Should he continue to misbehave, the next "walk" would not be so refreshing. The time will soon come when just to mention the idea of going outside will recall the unpleasant experience there, and will get a quick response. Remember also that commendation is very important in all fields of training. When your child does sit well, commend him, and he will glow inside.