Heath – “It comes from “1” Rosh Hayeshiva -so if you’re his Talmid don’t say Gut Shabbos before Shabbos.”
Is his name Reb Akiva Eiger???
Reb Akiva Eiger paskens in his glosses to S.A. that when a person says Gut Shabbos (“Shabbata Tova”) he is making kiddush midoraysa!
This would be a kabbolas shabbos if said on Friday after plag hamincha. It would be followed by an instant issur melochah!!
Therefore, no matter who your Rosh Yeshiva is, one must refrain from saying Gut Shabbos on erev shabbos. Better to say “a gutten EREV shabbos”.
On the other hand, once you are mikabel shabbos, EACH time you say gut shabbos during shabbos, you are mikayem ANOTHER mitzvah d’oraysa of Zochor. You get extra mitzvos by saying gut shabbos!!
There is no maximum “limit” to how many times a person can make kiddush on shabbos! Each is a mitzvah!! (I am talking about SAYING a form of kiddush, not drinking the kiddush!!)