Yes, you can say "From tomorrow" or "From Monday," and both are correct, but there are slight differences in usage:
* "From tomorrow": This is perfectly fine and refers to the day after today.
* Example: "From tomorrow, I plan to read a new book."
* "From Monday": This is also correct, but it’s used if you're referring to a specific day of the week (in this case, Monday).
* Example: "From Monday, I plan to read a new book."
Both work, so it's a matter of which sounds better to you depending on when you're planning to start.