HIM Training and Vacation

I'll be doing the Vineman Half Ironman this July, and it will be my first try at the HIM distance. I'm planning on using the BT Beginner HIM plan with some modifications (more biking), and the 20 week plan would start on March 1st.

The problem with this grand plan is that on March 1st my husband and I will be arriving in Rome for a two week vacation around Italy. I'm trying to figure out what to do about basically missing out on the first two weeks of the plan. I'm bringing running shoes with me and I know we will be doing tons of walking but our schedule is pretty tight since we're trying to fit in a lot of cities so I think dedicated training time will be limited.

Should I start the plan two weeks early to stay on the schedule, then take two weeks "off" while in Italy and start back up with week three when I return? Or just cut out the first two weeks totally and start with week three when I return? The volumes in week 3 don't look to be too crazy of a jump for me.

Thoughts BT? Thanks!