The early one can probably be discounted because it could just be swallowed air. Anything later could indicate urease activity where the acid is being neutralized by bacteria producing carbon dioxide gas which leads to burping.
Maybe a lot of the gas is coming out the other end. lol jk
This is not a conclusive test by any means but it does indicate that there could be a problem and that you might have some urease bacteria in your stomach causing the problems.
There could be several problems. A nervous system problem which is lowering your stomachs acid production which could of allowed bacteria to colonize your stomach. A nervous system problem might be due to poor absorption of nutrients over a long period, B12 needs stomach acid and so do essential minerals such as magnesium and zinc.
Bacteria could be fermenting food in your stomach or it could possibly be as I first suggested due to a weak? urease bacteria. It could be a combination of all three. It is all a lot of guesswork and all that you can do is to try to find more clues.
Another test is to consume sodium bicarbonate mixed in water on an empty stomach. Then time how long it takes you to burp. This test did not work well for me. It took a very long time, over 5 mins for very minor burps. The longer the time, the less stomach acid that is being produced. It's the first test that I did which made me first consider lack of stomach acid.