Depends on the matchup and the mindset of your opponent and what percentage you are at.
I am a Ganon main, I typically get the pleasure of playing Marth or spacies on battlefiled. If I haven't taken much damage I'll typically wait till they drop then perfect waveland to take the ledge. Invicible regrabs that they can't do anything about until their invincibility wears off. That alone is usually enough to be frustrating if they remain calm then I can reclaim the stage in any number of ways to include invincible ledge dash.
If they get mad and frustrated then you can take advantage of that to get an early stock. Usually I can do this by using Ganon's invincible grab from the ledge frames. Take a look at your character, analyze the most safe/annoying option that you have. If you play someone that can regrab safely to stall invincible frames then see if you have the proper tools/skill to exploit that and make their invincibility frames.
The first thought that will probably go through your head when you get a stock up is that you want to keep it. That is a good goal. However, don't become focused on that to the point that it affects your playstyle and robs you of the advantage that you established. If possible, create a goal of taking a second stock before he can take one of yours. Make the goal of dealing a certain amount of percentage if you have no way to take the stock. Turn little advantages into big advantages so that your micro decisions help to contribute to a macro goal.