(We need more info about your game and skill level)
answer: depends on your goals
Obviously, if you don't have positive income at 0% research, then it is probably time to stop expanding until you work on your economy and get Currency (very important tech). If you start losing gold at 0% research then your units go on strike - including workers - and then disappear completely.
There is typically or generally two ways of starting out a game - at least on most maps with AIs in proximity.
1) If you have lots of uncontested land to settle, then rex to a near break point, then build economy
2) Or build just enough cities to do an early rush of some sort. Depending on map, difficulty, and proximity of AIs, this can be done with 1 to 6 cities. yeah, you can rush with 1 city. Again, all depends on what you need or want to do.
Economy is a different matter though as far as learning. This is something everyone needs to learn...how to balance expansion and economy. More cities means more maintenance costs in Civ IV, so you must learn how to offset those costs.
"decent military"? - A decent military is something you can put into action immediately to conquer the AI. Otherwise, there's no point to a "decent military"
Don't know your skill level or the settings you play. Don't know if this is a one off question or you are desirous of learning to play the game better. Regardless, the Strategy & Tips forum is a great place to learn the game.
(edit: actually, I should really say that there are 3 ways and actually failed to mention a very common approach, especially on high levels. Basically, that is to expand to..say..4 to 6 cities and mainly focus on economy building and research to eventually setup an effective mid-game military strike. However, this approach is in some ways similar to #2, in that it is flexible early game. The main thing is not to let you economy tank to badly early on so that you can keep a nice research pace going. Of course, there is much much more to all this than what I'm saying here..but just answering the question)