As a solopreneur, how do you balance marketing with product development?

have a schedule every day do marketing activities

Morning: Focus thinking: product development Midday: 2h pause doing workout and eating (naturally switch to diffuse mode) Afternoon: Diffuse thinking: Marketing & creative

One way I have figured out is by cycles of two weeks. Two weeks of development and then defining two for running marketing experiments. Make them strict i.e. no jumping to code or vice versa.