The appropriate greeting at 4:00 PM or after depends on the cultural norms and local customs in your region. In general, the distinction between "good afternoon" and "good evening" can be subjective and may vary between different cultures and social contexts. However, here are some common guidelines:
"Good Afternoon": Typically, "good afternoon" is used from around 12:00 PM (noon) until late afternoon, roughly until 5:00 PM or so. So, at 4:00 PM, it would still be considered acceptable to use "good afternoon" in most cases.
"Good Evening": "Good evening" is usually used from around 5:00 PM until late at night. As the sun starts setting and the day transitions into the evening, this greeting becomes more appropriate.
As you can see, the transition time between "good afternoon" and "good evening" is somewhat fluid and can vary depending on the cultural norms and personal preferences. If you're unsure which greeting to use, you can opt for a more neutral greeting like "hello" or "hi" that doesn't rely on specific time-related distinctions.
When in doubt, observe what people around you use in similar situations and follow their lead. The key is to be respectful and polite in your greetings, and most people will appreciate your consideration regardless of the exact phrasing you use.