Adding Weight to Bodyweight Exercises

At what point should one start attaching more weight to themselves for body weight exercises? I can do about 10 pull ups in a row and about the same amount of dips with just my body weight, but I’m pretty exhausted by the last rep. Is there a specific number of reps I should be able to complete with just my body weight before I start adding more weight using a belt?

You can add weight now!

10 is a good number to start adding weight at IMO.