Nothing to worry about unless you are riding at high speeds (over 60 MPH / 100 km/h).

I've changed tires on my Honda ST 1100 - a heavy, high-speed touring bike - at sites in Africa where there were no facilities to balance the tire. On one occasion only, I noticed that I had an out-of-balance problem (vibration) at speeds above 80 MPH (130 km/h), so, I just stayed below that speed until I could remove the wheel and balance it.

All the other times, I didn't notice a problem at all - I just left the existing weights in place when I installed the new tire on the wheel.

Grant makes a good point - balancing the entire wheel assembly (the metal rim and tire together) is what matters. After having bought well over 40 tires for my motorcycle during the past 20 years, I've noticed that when a shop does balance the wheel when a new tire is installed, the balance weights are almost always in a very similar position to where they were for the previous tire. This suggests to me that the metal rim is more likely to be the out of balance problem than the rubber tire.

As for "where the dot" goes on tires that are marked with a balance dot, it is my understanding that you line the dot up with the valve stem. This is also the advice given by Yokohama and Dunlop, two major manufacturers of motorcycle tires. I suspect that all tire manufacturers follow the same protocol.

Michael