Three steps to a published week.

A project is one timetable — a term, a season, a group. Your first one is set up for you the moment you start, so there is no blank page. A new one needs a name, a start date and an end date, and that is the whole form.

The dates do real work. They tell people's calendars when the timetable stops repeating, and once the end date has passed the project will not build a new timetable until you move the date — so a finished term cannot be reshuffled by accident.

Events are the things that need to happen — a class, a lesson, a workshop. For each one you say how many times a week it runs, how many people fit, which days it is allowed on, and the earliest and latest it can be. If it has to be at a set time, say so and it stays there. Attendees are the people who need placing.

Instructors and rooms are entirely optional. Add them and they are scheduled too — who can teach what, when they are free, which room is big enough — and never double-booked. Skip them and they are simply left out. Most projects start without either.

Tick people into events yourself on a grid. Import your list of names and emails from a spreadsheet. Or share the project's sign-up link and let people choose for themselves — no account, no app, no password.

A sign-up does not have to be all or nothing: someone can attend two of the four sessions. And you can mark a sign-up as high priority, so that person comes first when there is not room for everybody.

Click Auto-schedule. Before it starts, it checks for the problems that would waste your time: someone who is never free, an event that needs more hours than you allowed it, more people than there are places, an event that needs an instructor when nobody suitable is free. Small problems are warnings you can carry on past. The genuinely impossible ones stop it there, and it names the event and how to fix it.

How long it takes depends on how much there is to fit in. A small project comes back in seconds, and a big one is given the time it needs — a couple of minutes at most.

You get one of four answers, and they mean different things. Best possible — there is no better timetable than this one. Stopped at the time limit — a good timetable, and it tells you how much better another go might do. Ran out of time — no answer yet, which is not the same as impossible. No schedule possible — two of your rules cannot both be true, and something has to give.

Anyone who could not be placed is listed with the reason: not free at any time the event runs, every session already full, clashes with another event they signed up for (and it names the event), or the event has no time that fits.

This is the part most tools do not have. Lock a session and its day, time, instructor and room stay exactly where they are; the next time you auto-schedule, everything else is rearranged around it. Locks carry forward on their own, so you can lock a few, run it, lock a couple more, run it again, and arrive at the week you wanted.

If a lock can no longer be kept — you changed the event, or the room went away — nothing breaks. The lock is dropped, the timetable is still built, and you are told which locks were dropped and why.

Scheduling tools normally throw the whole timetable in the air every time: add one person and everything moves, because the new arrangement is a hair better on paper. That is no good to the people who already rearranged their Tuesday.

Here a new timetable stays as close to the last one as it can. Anything that can stay where it was, does — but never at the cost of anyone's place. Add one attendee, and one thing moves.

Every timetable you build is kept as a draft. Put two side by side and see exactly what changed — which sessions moved, who gained a place, who lost one, and which instructors now have a different week.

Publishing is the moment it becomes real. Nothing an attendee sees changes until you publish, and their personal page always shows the published week, never the draft you are still working on.

When you publish, every attendee with an email and at least one session gets their timetable. Every instructor teaching at least one session gets theirs. People with nothing on are skipped rather than sent an empty week.

When you publish a change, you do not have to email everyone again. Send to only the people whose week is different, and the email says what changed: which class moved, from when, to when. Someone who lost their place is told that plainly, rather than being left to compare two timetables.