Around 5 hrs to fully metabolise caffeine. Physically you would be fine in a day.

The habit, however would take longer to get over. That depends on your psychology, I know I can’t just replace my morning coffee with tea, because it doesn’t feel right.

I usually have my last coffee at around 2pm, so by the time I get up in the morning, there is no caffeine in my system. The feeling of drinking coffee and tea is different for me, it’s not just about the taste.

Try using “to the best of my knowledge”, I find it is indicating that your knowledge is not complete.

But it also indicates you have thought of the situation.

Read books.

Really anything, philosophy is great but some don’t have the patience for it.

If it’s graphic novels or “kids” books, it’s all good. Spend a bit of time every day reading.