"Up until that time" sounds awkward -- is there a better way to say it?

Maybe I'm having a bad day, but I've just written a sentence similar to this one, and it doesn't read well for me, but I can't think of anything better right now:

The task was to build a new accounting system; up until that time they had been doing everything by hand.

Solution 1:

A good word for this would be hitherto.

The task was to build a new accounting system; hitherto, they had been doing everything by hand.

Solution 2:

I would use until then.
Until, in sentences like the kidnappers have given us until October 11th to deliver the documents means up to.

Looking at the Corpus of Contemporary English to see how much frequently the phrases until then, up until then, up until that time, and until that time are used, I get these data (the frequency is given in per million):

If I look at when those phrases are used, I get the following data: