You can take out the foreign health insurance at any time before the start of the trip – the first day of the trip is at the same time the date of commencement of the insurance. The insurance ends on the last day of the trip.
The price for individual insurance is dependant upon age (up to 21 years (21th birthday) or 21 - 39 years ). This calculation is determined based upon the age at the start of the insurance period.