Basically - just create small objects as much as you feel like and then if it turns out to be a problem, start looking at pooling.
Large objects or objects which are expensive to construct (often the same thing) are usually best pooled.
If you have a look at my games Alien Flux and Super Dudester, can you spot the difference? Flux used a lot of pooling - all the bullets, lasers, and particles are pooled. Super Dudester uses no pooling at all. Flux runs a little better on very low end systems, but the effort is simply not worth it now.