They are all pretty much interchangeable. I don't think that one is much more formal than another.
Like an adverb phrase, you can put it at the beginning of the sentence with a comma or you can put it at the end of the sentence, or even in the middle.
examples:
He was working, up to now, at the bank.
Until just now, he had a good job.
I have had good luck with driving so far.