Google sequential timer
> bg
The first hit was a two stage from delabs with a schematic, but it looks a fair bit complicated and possibly over my head. Then again it is well annotated and they say more stages would be added, there are also additional links for design considerations. It seems that it may require a bit more experimentation and relearning about digital design than I have time for at the moment, but I will study the page and see what I can make of it.