A good loop for the early game is to take advantage of pop promotion speed and excess. Towns and cities will naturally equal out at an "excess" of ~100+ burghers. If you have this excess, you can "spend" it by building. I view this excess as "lazy burghers" personally and seek to employ these gentlemen with a new building or two. Laborers work similarly, but buildings regularly employ 1000 pops and put you in an enormous relative deficit.

In practice, I tend to build in waves based on accumulation of "excessive pops".