Yeah.. realising I was not making a distinction between greenhouse effect (e.g. increased rate of warming), and the result (e.g. actual increased heat content/temperature. I think the rate of warming increase is basically instant, but yes, it takes some time for the temperature levels to catch up.

I don't know if I was explicitly taught it at uni, buy I have always understood as a climate scientist that GHG emissions started before the industrial revolution (albeit small). I think that's common knowledge in climate science.