I allowed my children to cry it out when I was sure that I had done everything possible to make them comfortable. Things like diapering, feeding and snuggling should all be attempted first. Sometimes it's hard to know what is making them cry, it could be teething or colic, and sometimes even that they're getting ill(checking thier temp. can rule out fever). I would let your child cry it out for atleast 10 minutes and just make sure they don't cry hysterically. Repeat this in intervals going in every 10 mins, and soothing them, you can definetly wait longer if they aren't crying completely and maybe just fussing. If you find that your baby isn't falling asleep and you need a break ask your partner or someone you trust to take over and give you a break. Best of luck!!!