Until you register the system, the warranty will reflect the date the system was shipped to Best Buy (or its distributor - Ingram Micro, etc.).
Transferring a warranty to Israel, as I recall, is dealer-dependent. Dell does not have a corporate support presence there -- all service/support/sales are through authorized dealers. I'd contact a local shop that sells Dell systems to see what they say (be prepared for them to tell you they won't support what they don't sell, in which case you face the very real possibility that the system will need to be returned to Best Buy or Dell USA for repair).
The warranty transfer requirements:
1. The system must be sold in Israel - if it's not, no transfer.
2. The warranty must be upgraded to onsite service (check with the local dealer about this possibility).
3. You must register the system with Dell.