Hi!
I’ve faced the same problem and found a few things that make joining much faster. First, using a laptop or desktop usually works better than mobile devices because browsers load the game more reliably. Chrome or Edge tend to be the quickest, especially if you clear cache occasionally. Timing definitely matters.
When you go to kahoot join game, having the code ready and entering it a minute before the start can help you avoid delays. Also, make sure your internet connection is stable and avoid VPNs, which sometimes slow things down.
Some people keep the join page open and refresh right before the game begins.