The short answer to this is to wait until any swelling or bruising has gone down. In some people, there may be none, whereas, in others, a large bruise may take 2-3 weeks to fully settle. It’s best to wait this out so that you can see what the ‘new lips’ look like with just the new filler and not the temporary effects of swelling or bruising, otherwise. Then once you can see the result from the first treatment, it’s easier to give make adjustments or enhance what you’ve already done. Easier, but still not easy. And you can give the second treatment anytime after these temporary side effects have worn off. As when you go back for more, it can be harder. Issues to consider are:
1) Resolving asymmetry which was either there before and not fully corrected or created by the first treatment
2) treatment of lumps (either caused by you or someone else)
3) Generally making them even bigger than before.
I suggest having a system. In my system, I start by apportioning how much of the 1ml to use on the top lip and then the bottom lip. Then I apportion this to the left and right sides. e.g. say we decide with the patient that the top lip needs 0.4ml but the bottom lip needs 0.6ml, but the top left is bigger than the top right, then the relatively simple decision can be made next: how do we distribute the 0.4ml between the left and right sides of the top lip, to even out this asymmetry. Almost any system will do, but a system is necessary.
I’ve written about this before, here. https://visage-aesthetics.com/lumps/
My blog here shows short and simple advice on how to avoid those unwanted lumps and how to prepare your patient for those they may expect to discretely feel.
Generally making them even bigger than before
If things are pretty symmetrical and there are no lumps, this is relatively easy compared to the previous two issues. Simply do more of what you’ve already done. It’s best to use the same filler again though, or at least the same brand. It’s best not to mix brands, as this is in the small print on most brand leaflets, and if you don’t follow that guidance, your insurance company may not cover you if something were do go wrong.