My son has been able to wave and say bye for months now. He does not always want to wave goodbye or say it but when he chooses to it is completely adorable! Recently, in the morning as I am grabbing him out of the crib I tell him to drop Bunnie (his lovie that has a pacifier attached to it) and that he will see Bunnie later (he only gets to see Bunnie with the pacifier during nap and bedtime at this point). He drops Bunnie into the crib and waves goodbye as he is saying “bye bye”. In his little toddler voice, it is just adorable!