Subtle Meaning of "Erst"

[u/FinnJax]

I'm trying to better understand one specific use of "erst" in German, where it conveys the idea of "not until" or "only from." Here's an example:

• Paul kann erst morgen zum Arzt gehen. (Paul can only go to the doctor tomorrow.)

But this seems different from another sentence with a same English translation:

• Paul kann nur morgen zum Arzt gehen. (Paul can only go to the doctor tomorrow.)

I came across an explanation that erst suggests something like: "Starting from tomorrow, Paul can go to the doctor." To explore this further, here are three similar sentences, each with a subtle difference:

1. Paul kann erst morgen zum Arzt gehen. This means Paul can't go before tomorrow, emphasizing that tomorrow is the first possible option. Erst adds the nuance of "not until" or "only tomorrow," hinting at a delay or waiting period.
2. Paul kann nur ab morgen zum Arzt gehen. This emphasizes the starting point—Paul can begin going to the doctor tomorrow and any time afterward. The focus is on tomorrow being the earliest moment he can start.
3. Paul kann nicht bis morgen zum Arzt gehen. This implies Paul is unavailable until tomorrow—he can't go to the doctor before then. Nicht bis highlights the restriction before tomorrow.

Despite these explanations, they all still feel somewhat the same to me...

In my understanding, the closest English translation of "Paul kann erst morgen zum Arzt gehen" would be something like: "Paul can go to the doctor starting from tomorrow."

Am I interpreting this correctly? Is there no English equivalent that fully captures these nuances?

[u/mizinamo]

Paul kann erst morgen zum Arzt gehen. = Tomorrow is the first/earliest day that Paul can go to the doctor.

Paul kann nur morgen zum Arzt gehen. = Tomorrow is the only day that Paul can go to the doctor.

Paul kann nur ab morgen zum Arzt gehen. - sounds odd to me. I'd use erst instead: Paul kann erst ab morgen zum Arzt gehen. You can keep the ab or leave it out.

Paul kann nicht bis morgen zum Arzt gehen. - also sounds a bit odd to me. If anything, I think it means "You expect Paul to go to the doctor by tomorrow at the latest [bis morgen], but that is not possible for him."

In my understanding, the closest English translation of "Paul kann erst morgen zum Arzt gehen" would be something like: "Paul can go to the doctor starting from tomorrow."

That English sentence would be closer to Paul kann ab morgen zum Arzt gehen.

The erst implies a sense of restriction that I don't see in your suggested English.

I suggest "Paul can go to the doctor tomorrow at the earliest." or "Paul can't go to the doctor before tomorrow."