Is it a good idea to take whey protein isolate as a recovery drink after i do the insanity fitness program? and before bedtime?

Yes and no: The whey protein drink is ok any time of day. The intense exercise before bed time that is not a good idea since it could significantly affect your ability to fall asleep. Even though you did not complain of insomnia, google "sleep hygiene" to get answers.

Maybe, but..: Insanity is a vigorous exercise program that engages all major & core muscle groups, stimulates the release of glycogen stores and the rapid and efficient uptake of oxygen to fuel activity. Recovery from the demands of such a program requires some protein and also a high GI food to promote growth and replenish glycogen. Adding some fruit or dextrose will do the trick!