"Self isolate until"...

[nanbread]

We have been informed by the app to self isolate until the 19th, does this mean we can leave the house on 19th, or 20th? It's not clear...

It should have a time on it too, mine is 20th Dec at 23.59pm so I'm free on the 21st. Apparently though a few days have been taken off the isolation period so I'm expecting (hoping) it to change

I went for the day after.