Well the short answer to your question, as @arkhitekt has said is - polish then wax / sealant. I also have a year and a half old Civic in Karachi, and that is the max I would do.
Which exact products do you have and what is the color of paint?
If you go by textbook, then wash, clay, polish and finally wax / sealant. Clay becomes more useful in scenarios where car is not cleaned regularly and combo of extreme sun and dew, causes contaminants to bond to the paint. This is especially true if car is parked under tree where there may be tree sap / birds droppings. Clay is even more useful if you have odd color like red or blue where it will bring it back to its 'original' shade. Problem with clay is that its not easy for beginners and in a place like Karachi, there is more likelihood of dust getting trapped under the clay bar realtime and marring the paint. That is why, personally, I would clay very seldom and always follow up claying with polishing. Ideal product for a claying beginner is Nanoskin Autoscrub fine grade sponge used with Nanoskin Glide.
Now coming to polish. This, personally, is my favorite step and a polish used with a normal foam pad is not likely to 'cut' paint in any harmful way. Go panel by panel and notice how paint starts making that 'chu chu' sound evidencing that it's super clean!
If, by glaze, you mean something like Meguiar's M7 Glaze, then that's a useless product, if you ask me. No need to apply it. If you're skipping polishing, after claying, then it might be useful to some extent. Glaze, essentially is a substitute for polish, and I can explain in detail why I don't like it.
Finally, M21 Sealant, yes of course it can be applied to new or old car, but prep (in case of 1.5 yr old Karachi car) is key.
