Delivery Pipeline Step 3: Size and Plan
Size your backlog relatively, without converting to hours. Pick the smallest story as your unit and compare everything to it. Then set a work-in-progress limit of one or two and hold it. Work one iteration, and at the end record what you completed against what you expected. Do not adjust the estimates to match; record the gap. After three iterations that gap tells you your actual capacity, which no amount of estimating up front would have.
Built it in both languages?
Mark it done once your Python and JavaScript versions both run correctly. Honesty here is what makes the dashboard useful to you.