My last-minute attempts to add at least an optical hint on which part of the blocks to look out for unfortunately didn't get me anywhere, so I had no update on that Friday evening...
To some degree the independence between when the blocks move and the wheel turning is on purpose in order to avoid possible lock-steps making the game either unplayable (as in, whatever you do the colours never match) or far too easy and boring (like they're always in sync and the only timing you would have to check out for is when the blocks are sitting on a tile).
Also, I began developing by setting up the playing field and getting the block movement done. In the first iterations one could only start a block manually with a key... Reworking the block movement would have been quite a lot of work.
In my first concept it would have been much more tactical but I couldn't think of a good way on how the different parts would interact with each other, so I settled with it being more Tetris-like and getting a playable game done.
I think I might re-visit all those ideas at a later time. Perhaps there will be a GemTris Tactics or something at some time...