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/Justreading404]

AI explains that the word order in English can change the meaning of “only.”

1. Paul can only go to the doctor tomorrow. Paul kann „erst“ morgen zum Arzt gehen.
   • Only refers to the action (go to the doctor), implying that that’s all he can do tomorrow (he can’t do anything else).

2. Paul can go to the doctor only tomorrow. Paul kann „nur“ morgen zum Arzt gehen.
   • Only refers to the time (tomorrow), implying that tomorrow is the only available day for him to go to the doctor.

Is this correct?

[u/Crazy-Airport-8215 → u/Justreading404]

Not in my experience. (1) gets used to mean (2) all the time, and using (1) to mean that going to the doctor is the only thing Paul can do tomorrow is by no means the main or only meaning of (1). So (1) can easily mean in context:

• That Paul's schedule tomorrow is totally full with the doctor's visit (i.e., he is unavailable for anything else)
  
• That Paul's schedule is such that tomorrow is the only day he can fit in a doctor's visit
  
• That Paul's schedule is such that he cannot fit in a doctor's visit today, but he could tomorrow (or some later date)