Herceptin with taxol

I will be starting my chemo treatments on the
29th of November. I will recieve taxol(or taxotere) with herceptin once every 3 weeks for 18 weeks, then will continue the herceptin for a full year. I am curious as to when to expect my hair to fall out. I want to shave it off before it falls out on it's own, I plan on sending my long hair to locks of love. I'm sure many of you have had this same treatment and wonder when your hair loss occured. the answers I get from the onc. are very vague. What are your experiences? Thanks all.