CA glue of any common kind shouldn’t be relied on to keep on the fins of a mid-powered rocket. It’s sole job is to tack the fins in place so they don’t move around while the fillets are drying. As far as I can tell by text post, you are doing things correctly. I use medium cure and a bottle that can cure it near instantly once the fins are where I like them.
When it comes to JB weld slow cure versus titebond, depending on the exact products being compared, either could be stronger, but generally JB weld will have an edge in strength.
However, titebond is cheaper, easier to sand, and usually plenty strong for midpower rockets. I think titebond is a non-foaming glue but some wood glues (like gorilla glue) do foam. Do a test on some scrap material before hand to make sure you are satisfied with the result.
Titebond also has a limited working time of 5 minutes for the first two products and 8-10 for their fancier glue if my memory serves me right. This should be plenty, but if you try to work past this, this could significantly weaken the result.
Next comes epoxies. JB weld is a type of epoxy with lots of fillers already mixed in that isn’t particularly strong and modestly expensive, but can handle somewhat extreme heat much better than its competitors in the price bracket.
For high power rockets, we use strong epoxy for practically everything, except for attaching objects under moderate stress to high temp components like a engine retainer to a motor tube or the root of fins to the motor mount.
I consider most 5 minute epoxies to be crap and wouldn’t bother with them. 30 minute epoxies tend to be nice and strong. I use more specialized types for my rockets, but usually 30 minute does nicely for most hobbyists.
The best part of epoxies is that you can tailor them to your exact needs. You can thicken them to practically any consistency you desire. You can add chopped carbon fiber to make an incredibly strong fillet (it’s on a whole different level than anything we talked about before). You can make it sandable and so much more.
It can be cheap in largish amounts for the general use stuff or very expensive for specialized versions.
However, it can also be bad for your health especially after repeated exposure. You don’t want to get it on your skin or breathe in the fumes from certain volatile types or the particles of some kinds of fillers.
The basic types can be squeezed out by eye but the nicer types will require a scale to measure out precise amounts by weight of the two components.
I’m used to using epoxy for high power rockets so I use it for pretty much everything.
However, you’ll likely be best served with a non-foaming wood-glue and CA to tack the fins. However, if what you are doing now works for you, you don’t have to change.
If you have any further questions or want clarification, feel free to ask.