Maintenance Herceptin

Hi. I'm just completing my 6th chemo/herceptin session and will be going onto maintenance Herceptin every 3 weeks for a year. Have surgery and possibly radiotherapy to look forward too but putting on my positive hat I've a holiday booked layer in year (booked before diagnosis) which I'm hoping to make. Booked for a month so just wondering if anyone has experience of stretching time between injections Or getting an injection abroad? Can reduce hols to three weeks just if it was possible would be a great post treatment treat. TIA.