What is the best bedtime for babies who are sleep training?

Many people think that if you exhaust your child, it will make it easier, but it's actually more difficult to work with an over tired child. Many experts suggest very early bedtimes, but I find it to be more effective to choose between 6:30 and 8:30 p.m. and that also incorporates a one-hour window from when the last parent arrives home to when the little one goes to bed.