Absolutely make a formal schedule and stick to it as best you can. Schedule a day that you would want and be satisfied with. Separate work time and leisure time, otherwise as a solo dev you feel guilty for not working all the time, which makes it harder to start work. Don't expect yourself to "want" to start working all the time, because you won't. That's the mistake a lot of people make. Get started on small, easy tasks that can ramp you up and get you into flow state.
Ex.
8am - out of bed, make breakfast, no phone usage
9am - start working (and make sure you have specific tasks to work on)
12:30pm - lunch break + go for a walk and listen to podcast
2pm - continue working on specific tasks
5:30pm - leisure time + make dinner
7pm - workout
8:30pm - shower, get ready for bed
9:30pm - sleep
Ex.
8am - out of bed, make breakfast, no phone usage
9am - start working (and make sure you have specific tasks to work on)
12:30pm - lunch break + go for a walk and listen to podcast
2pm - continue working on specific tasks
5:30pm - leisure time + make dinner
7pm - workout
8:30pm - shower, get ready for bed
9:30pm - sleep