You wouldn't ever say "the time is come," it would always be "has come." "The time has come for me/us" or "my time has come" can mean someone's about to die, but it can also mean something you've been waiting for for a long time is happening. If you've been studying English for years and then have to go to America, you could say "My time has come" as in "The time has come for me to finally use the English I've been learning." If you want to say it's finally a certain day of the week, you'd usually just say "It's finally Wednesday/Sunday" or something similar.