How to say "at this rate"?

Question

One of my friends has been making a real effort talking to me in Japanese every day. I wanted to say something like "If we continue at this rate I will be able to speak by Christmas". The dictionary thinks that at this rate is この分。

So my question is, is it natural correct Japanese if I say

この分に続いたら、クリスマスまで話せるようになるわよ

?

I suspect that not. It feels like there is a word missing like この分のスピードに or something like that.

Answer 1

There are many ways to say "at this rate" in Japanese but the more common ones are:

「この調子{ちょうし}だと/なら」、「このペースだと/なら」、「このままいけば」, etc.

Any one of these would fit your sentence with no problem.

Regarding 「この分{ぶん}」, you could use it by adding 「なら」 or 「だと」 to it, but not 「に」 as you formed it. You cannot say 「この分に続いたら」, though it was a nice try. You can say 「この分だと」.

Note: It is 「クリスマスまでに」 and not 「クリスマスまで」.

～～までに = by ~~

～～まで = until ~~

Use 「まで」 and you will be saying that you are only allowed to speak Japanese until Christmas. You can speak Japanese after Christmas, too, you know.

Answer 2

I would say

このまま続ければ、クリスマスまでには話せるようになるわよ

for

If we continue at this rate I will be able to speak by Christmas.

Caveat："If we continue at this rate" literally (= in a verbatim fashion) translates into "私達がこの速さで(努力を)継続すれば". See 1.1 of this -> http://www.oxforddictionaries.com/definition/english/rate .