It came to a shock on me that saying have a blessed jummah (Friday) is an innovation in Islam because it has never been said by the sahabis nor by our beloved prophet (saw).
Saying "Eid Muarak" or any good greetings for Eid is not a bidaah since the sahabah used to do it:
Jubayr ibn Nufayr said: “At the time of the Prophet, peace and blessings be upon him, when people met one another on the day of `Eid, they would say: Taqabbal Allahu minnaa wa minka (May allah accept yours and our good deeds).”
[Reported by Al-Albani with an authentic chain of transmission]
As for Jummah. There is no harm in doing so. Unless you consider this as a sunnah (keep doing it every Friday) or you think saying "Jummah mubarakh" will increase your good deeds. Then this is considered a bidahh.