Translation of “If so”

Question

How do you say "if so" in German?

Do you have some time? If so, I would like to speak with you.

Would you say "wenn ja"?

Haben Sie etwas Zeit? Wenn ja, ich möchte mit Ihnen sprechen.

Answer 1

Almost perfect.
Yes I would use "Wenn ja," , but if you use this you need to invert the structure of the following sentence, due to the implied "dann":

Wenn ja, [dann] möchte ich mit Ihnen sprechen.

Alternatively you could also say: "Falls ja", "In dem Falle"
a little discurteous: "Dann" because this implies you expect the one you asked to have time

As suggested by @Toscho and @Dustin:

• "In diesem Fall,"
• "Falls / Wenn dem so ist,"

And as a more polite Alternative:

Falls sie Zeit haben, [dann] möchte ich mit Ihnen [über Thema xy] sprechen.