Who hasn't seen Mr Michelwhite in the classic Zulu?
Oh, yes. The reason to attack the Zulus early is that, although you may not win, you'll certainly stand a better chance than if you leave them unmolested. The tactics are very sound, very effective.
If you do the nuke thing, and it is fun, do it before anyone else has them, and preferably when the opposition are too weak (numerically and / or technolgically) to counter attack altogether: 'cause thy're after you. Also the planet does tend to get real messy, real quick.