If they're not leaking or rusting out, sure you can wait, but they are going to wear over tens of thousands of miles so I typically replace them every 50K mi. whether the bounce seems excessive or not, unless I'm soon to get rid of the vehicle and they're not terrible yet.
Things like bounce, that get gradually worse, aren't as night and day easy to compare until they're replaced, but don't cheap out and put generic Chinese brand struts on or else you may soon be worse off than you started. Go to a car forum for your particular make/model/generation and solicit opinions from fellow owners who have been through this already.
Keep in mind that if (assuming) you'll need an alignment, it can make sense to time the strut replacement along with another repair activity that makes an alignment prudent like worn suspension parts, a collision (even a bad pothole) causing an issue, or right before going to get new tires put on, so you're not paying for another alignment over and over (or else you bought an alignment package at higher cost to give you lifetime alignment but read the fine print for that).