The short answer
You cannot reliably catch 11:11 by remembering to look. The whole appeal of the number is that it arrives unannounced, and the moment you start trying to catch it on purpose you will miss it on the days you are busy, which are usually the days you wanted it most.
Every working method comes down to the same thing: let something else watch the clock. The four realistic options are a repeating alarm, a calendar event, a shortcut, or an app built for it.
1. A repeating alarm
Set a daily alarm for 11:11. It is free, it takes thirty seconds, and it works.
The trade-off is tone. An alarm is the same sound that wakes you up, it interrupts whatever you are doing, and there is nowhere for the moment to go once it has fired. Most people who try this turn it off within a fortnight because it feels like a chore rather than a moment.
2. A repeating calendar event
Softer than an alarm and easier to ignore, which is both the advantage and the problem. A calendar notification at 11:11 sits in your notification list alongside everything else and is dismissed with the same reflex.
It does have one real benefit: you can put a note in the event, so there is somewhere to write.
3. A Shortcuts automation
On iPhone you can build a time-of-day automation in the Shortcuts app that fires at 11:11 and opens a note. This is the most capable free option and the fiddliest to set up.
It also will not count down, so there is no sense of the moment approaching. It simply happens and then it is over.
4. An app built for the moment
This is what Orbdit is. You set a sync window to 11:11, or 2:22, or any time you like, and a countdown appears on your lock screen and in the Dynamic Island as it approaches. When it arrives the app taps you, and you have three minutes to write a wish.
The difference from the free options is the three minutes. An alarm gives you a noise. A countdown gives you the approach, the moment, and somewhere for it to land, and the wish is saved so you can read it back weeks later.
One sync window is free. If you follow more than one number, Orbdit+ lets you run as many as you like.
What to do on the days you miss it
You will miss it. Everyone does, and the number is not keeping score.
If it matters to you, log it late. A sighting written at midnight about a 11:11 you missed is still a record of the day. The point of the practice is the noticing, not the punctuality.