Brysing if a book can be read in 3 months then surely magick can be learned in 3 months! Common knowledge obviously.
Well it sounds fun in theory, but you might wish to come to a common goal. The YouTube Pagan Challenge for example is a series of videos answering a series of questions like when did you get started, what does magick mean to you, what does this season represent to you, who do you admire, stuff like that. Not really a spell a day, but still relevant. This path isn't just about spell casting, so perhaps research various things to study, questions to contemplate, and things to practice [like meditate for 30 minutes or observe the season] I don't know of any 'challenge' but I have come across a series of questions and activities over the years to help me at various points in my life when I was stagnant. Try getting a copy of Deborah Blake's 'The Goddess is in the Details' it helps further your study and gives questions/activities to help you on your next step.