Here's a real snoozer for you, but it's so important regardless of the boring content. How much toothpaste exactly should I dispense on my child's brush? The most current recommendations are:
*use a flat smear of fluoride toothpaste about the size of a grain of rice for children younger than 3 years old
*use a pea-size amount of fluoride toothpaste for children ages 3-6
Here I show off my underwhelming photo skills to depict the amount of fluoride toothpaste you can dispense on your child's toothbrush:
The key point here is that the American Dental Association's (ADA) Council on Scientific Affairs (CSA) recommends that caregivers should brush their children's teeth WITH fluoride toothpaste as soon as the first tooth comes in. Wow, good to know! It's hard to imagine putting the tiniest smear of fluoride toothpaste on the smallest brush available, and brushing your 6 month old teeth, but you certainly can.
Why is this good? "Home use of fluoride products for children should focus on regimens that maximize topical contact, in lower-dose higher-frequency approaches." 
In other words, brushing your child's teeth with a very small amount of fluoride toothpaste twice a day/every day is a great tool in your cavity-prevention toolbox. Fear not, if you plan to opt out of fluoride toothpaste, and read on.
An alternative is to brush at least twice a day with water, achieving the mechanical removal of any residue remaining from milk, formula, or baby food/purees. I also recommend Tom's of Maine fluoride-free, which contains xylitol if you don't prefer fluoride toothpaste for your child. The act of brushing itself is equally important in preventing cavities, and should be considered non-negotiable in every family. Don't feel guilty if your toddler fights it, not wanting anything to do with a session of brushing. You are not causing harm, even though they might try to convince you otherwise. So paste or no paste - that's up to you, but do start brushing whenever that first pearly white tooth makes an appearance.
1.Adair SM. Evidence-based use of fluoride in contemporary pediatric dental practice. Pediatric Dentistry 2006;28 (2);133-42