I personally think it does matter what days you work, as to qualify for JS allowance, you must be available to work on the days you are applying for. If it was me, and I wouldn't mention self employment until you actually have an income from this business. If you say you work evenings on your business you are not entitled to a full days claim from SW. For certainty, I would have a chat with the Citizens Advice Centre. They have exact information if you are unsure.