This is a very good example of an uneven stain. It looks as if you stained it in sections rather than staining it all at once. I think it can be improved by lightly sanding the darker areas with 220 grit sandpaper and re-staining with the same stain using a rag instead of a brush and allowing the stain to set a few minutes before wiping off. Wipe from one to the other in long strokes. Donít stop and restart in the middle of wiping.
If you still have blotching after a second application you can use a Toner in a rattle can to even it out.
If you don't have time to do it right the first time, when will you have time to do it over?