Should I keep on saying "Our Painter has painted excellently"

I had my home painted some days ago(ex:30 days). And I am telling this to my friend:
“Our Painter has painted excellently”.
Should I keep on saying this until my home get painted another time (next year)

Is “Our Painter painted excellently” not a correct thing in this scenario.

Thanks

Our painter (no capital letter) did an excellent job.
Our painter was excellent.

The job is over and done with, so there is no reason to use the present perfect. But it’s also not natural to say “painted excellently.” Try either of the two above.

(It’s nice that you’re happy with the job he did, and that you are recommending him to others.)

I got confused in this issue.
Whenever we want to tell that a work which was completed in the past, can I say “I finished the work”.
I heard/taught that when ever you use past simple like the example above, as a condition, I should give the time when was it finished.
Correct: “I finished the work in the last month”.
Wrong: “I finished the work”.

If I don’t give the time, I have to tell like this:
Correct: “I have finished the work”.
Wrong: “I finished the work”.

Is this correct?

It’s not exactly like that. You are not supposed to specify time when you use present perfect. You can specify time or just ignore it when you use simple past.

Our painter painted it a year ago. – Correct
Our painter has painted it a year ago. – Incorrect
Moses parted the Red Sea. – Correct

You use present perfect to talk about things that happened in the past, and have some effect on or relevance to the present.

For example, consider this scenario, John sends out for a pizza. He thinks he’ll take a shower before the pizza arrives.
When he’s back after taking the bath he finds an empty pizza box. He asks Jake what has happened.

John: Where is the pizza?
Jake: Sarah has eaten it. (the effect on the present is the pizza isn’t there now)
John: Where is she?
Jake: She has left. (the effect on the present is that she is not there now)

You can also use present perfect with adverbs like never, ever, always etc

Eg:

I have never seen a snake.
He has always been a great actor.
Have we ever invaded a country?