Like everyone has said, the OFHG and vanos line are typically done together. Plenty of "while you're in there" items to inspect as well if you DIY this big job. I would say start it early on Saturday AM and finish up by Sunday afternoon. Split into two days.

Here's my OFHG DIY guide on an X5 3.0i

https://www.youtube.com/watch?v=nYCgnUkDvJk

Since so much has to come out, not a bad time to do a water pump, thermostat, belts.