we had a manual switch at that time. I was new to the new england area and I grew up in a tropical country :-) so never had a habit to check before starting the shower.

Ah so this is one of those things where neither of you were really right or wrong. If you'd grown up in New England you'd have known that the "right" behavior was to turn the shower on and warm it up before you got in. Having grown up there myself I have to say it would never occur to me to turn a shower on while standing in it and I'd assume nobody else would either because it's guaranteed to be painful, even in summer and even when it's just water coming out of the tub faucet onto your feet. My family always left ours on shower mode and never had an issue for this exact reason. Always so interesting to learn about the little things people from other places do differently!

I think back then I used to get in the shower, turn on the tub faucet, and when it was warm enough, switch. to be honest I still do that sometimes by mistake :-)

> most showers I've used automatically switch back to tub mode

this is nice indeed, but not universal sadly

> Do you get in the shower before turning it on?

In some large buildings I've lived in, it takes like 1 second for the water to be warm -- it's magnificent. So yeah, if you have a shower-over-tub in that kind of place it is easier to get in, have the 12 ounces of cold water go harmlessly into the tub, then switch to shower.