Do you always go for to "Top Notch Infant" and "Happy Toddler" traits?

I usually age infants up to toddler immediately. I do generally play toddlers until they are ready to achieve the Happy Toddler trait though. If you have toys scattered around the house they'll develop imagination and motor pretty much without any help from an adult. The giant plushies help with social, also having a sibling. The two that require adult intervention to keep pace are Thinking and Potty.