DCF-How long can you wait?

We are just thinking preliminary steps on a move back in about 2 years but I cant seem to find out one thing that affects our timing. How long from when the visa is issued do we have to actually enter the US? I dont want to wait too long but I dont want to apply too early if we only have so many days to move. Thanks!

Once you get your approval at your interview you must enter the US within 6 months.

Certain documents (police certificates, medical exams, etc) are only valid for a certain period of time, so you don't want to start the process too early. We knew we wouldn't want to move until after the first of the year, so we started the process in July and had our interview in early January. That was just our experience and everyone's time frame is a little different.

Thanks so much! I was thinking it would be 3 months so 6 months help tremendously. I was also thinking the process was approximately 6-8 months so that fits with what I was looking at timeline wise. Its still about a year and a half before we apply but I want to make sure I know a good timeline so we are prepared.