Are the increases in CO2 equally distributed throughout our atmosphere or are most of the increases concentrating at specific elevations?
CO2 concentrations exhibit a diurnal pattern near surface level close to sources and sinks. Horizontally distribution is patchy and effected by the jet stream, weather and larger patterns of circulation.
While eventually concentrations will rise overall these patterns will still result in differing concentrations due related to sources and sinks and the above mentioned effects.
You can view visualizations from NASAs Carbon Monitoring System (CMS) here.
As the funding for a newer system has been targeted for budget cuts a complete answer to your question may or may not exist in the next couple of years.
While it does take time for a ground generated gas to diffuse to the upper atmosphere, for example, it will happen over several years.
The mass of the molecule makes little difference in the long run.
E.g., the deniers of old that CFCs causes ozone depletion claimed that the molecules were too heavy to reach the ozone layer. It’s a gas idiots!
NASA sent sounding rockets up to measure CFCs. They found the concentration uniform all the way up to the ozone layer. (And then it dropped it rapidly. Like there was a chemical reaction going on there. Hmmm.)
Look at the 2nd chart in Stranger’s link. This is from the top of a high volcano in the middle of the Pacific Ocean. Note how they can detect seasonal fluctuations mainly caused by plants thousands of miles away. And how uniform the average growth of the curve is. It’s not taking long for CO2 to get there.