Your sprint should start on a Tuesday or a Wednesday.
To provide some justification for that confident answer, here are some important requirements for your major sprint ceremonies:
- You need your whole team in the sprint ceremonies as often as possible.
- You want your sprint ceremony days to be as regular as possible (i,e, to fall on the same day of the week on every sprint).
- You need 2 consecutive days, 1 for review and retrospective at the end of the last sprint, 1 for planning the new sprint.
- You want your team to be focused and alert for both of these days.
I think we can all agree on these basic requirements. Here's how they affect the days of the week your sprint should start on:
- More holidays (and sick days) are taken on Mondays and Fridays than Tuesdays, Wednesdays and Thursdays. So if you want your whole team there, the chances are much better on a Tuesday, Wednesday or Thursday.
- Public holidays (especially in the UK and some other Commonwealth countries), tend to fall on Mondays. In countries that have a Christian history, Good Friday and Easter Monday always - obviously - fall on a Friday and the following Monday. This means you are almost certain to lose one or more ceremony days to a public holiday.
- Fridays are the day people are least likely to be alert and focused, and the day they are most likely to be thinking about leaving early (if your company has flexi-time or similar). That makes Fridays a bad day to have either reviews and retrospectives or planning meetings.
- More discussions of weekend shenanigans, sporting events, hackathons and whatever else people get up to, happen on a Monday morning than any other time of the week....except possibly Friday afternoon. This does not lend itself to an alert and focused mental state on either day
- Monday morning is often used for start-the-week meetings, email catchup, and so on. This will interfere with ceremony timing, or, harsh but true, the ceremony timing could be seen as interfering with "normal business". This is particularly important if you are still trying to get buy-in for agile at your company.
Ceremonies are supposed to be time-boxed, and everyone should be working their full hours every week (baring holidays or sickness), but let's be realistic about how people really are. We are not automatons, we get more tired as the week goes on, we have a life outside of work, and most of us get on with at least a few of our colleagues and like to talk about our weekend. This is normal. It's not wrong, it's not weird, it's not lazy, it's how humans are. Make sure your Agile implementation takes that into account, and schedule the start of your sprint on either a Tuesday or a Wednesday. You'll get a lot more out of your team if you do.