I can relate with a full-time job that is 50+ hours/week, and my free time these past few months has been putting portfolios/applications together and applying for a new position (fingers crossed, but competition is really tough in academia), I am rarely squeezing in daily practice. Study time, which I think is even more important, has been near-nil unfortuanately. When I do pick up my pen, I do as Jean suggests: I play. Sometimes when I'm really tired, oddly, I am most creative because the self-control brakes are weaker than normal. Science does back that up: being tired increases creative thinking. Plus, for me, calligraphy puts me in a meditative state and is the ultimate way to unplug and unwind before bed, so I really do try to pick up my pen no matter how tired, and even if only for a few minutes. During the busy time, I show myself compassion. I am not as critical as I am when I am studying in earnest. My advice would be to go with the flow of your day. To not have time for calli because you're busy with other matters (a CD!? How cool is that!!!) is a big difference from being lazy and not practicing because 'you don't feel like it' and watching Netflix instead (not that there's anything wrong with that on occasion either!). If you're too tired to pick up the pen at night, picking up a calli book to study instead is another option. But no matter what, try not to put so much pressure on yourself. Calligraphy is a neverending journey with different speeds of progression. You won't always be this busy, and will have more time to devote to the art after that CD.