And as for your main point - in some ways this reminds me of the health care debate. In both cases, the US is an outlier compared to its peers, and most foreigners as well as a large number of Americans think it would be better if its system was closer to that of those other countries.
But even if you accept that premise, and an equally large or larger number of Americans would not, it's far from obvious how one would get from here to there. You can't just throw a switch and start doing things the other way, and trying to make the transition could well make things worse before they get better. If they get better.
In the case of guns, the difference between the US and its peers isn't just in the laws. It's in the sheer amount of guns already present in the US, the movement of arms in both directions across the Mexican border, the levels of gun use involved in other crimes such as robbery, and so on. Simply changing the laws to those of other countries isn't going to automatically recreate the outcomes of those other countries.
I am in fact broadly in favour of gun control and very much not a fan of the NRA, but let's not pretend that this kind of thing is going to disappear overnight if the laws are changed. And as for the timing, I'm not sure it's so much about time, as it is about simply having the facts before you try using the tragedy for your cause - which can be almost immediately sometimes, but in this case it isn't.