Heck, if you always feed slightly small prey items you could do weekly for the rest of their life. These guidelines aren't laws. You can do what you are comfortable with. Young boas are hard to feed because they grow out of prey sizes soooooo quick. I've experienced a size to only be perfect for 2 weeks. Then all the sudden it's too small. Use your best judgement. The rule of thumb I read was to wait at least 2-3 days after all signs of feeding are gone before feeding again. For example... Our guy goes DARK when he's digesting. He will lighten considerably at almost the exact same time that any food bump signs are gone. At the same time... if his prey is too small he doesnt darken at all. Interesting huh? Observe your snake. Watch for signs of a chunky snake. As long as they aren't too thin or too round you're doing great! You'll discover what's perfect for him/her.