Foreign driving licenses are valid for 12 months following arrival. The license can be transformed into a Swiss driving license with the cantonal Road Traffic Licensing Department or the Residents' Register Office within this time period. The foreign driving license may no longer be used after this one-year period has expired.
It is advisable to apply early since the replacement formalities may take quite some time. Depending on your country of origin, it might be worth checking with the Road Traffic Licensing Department whether the driving license can be re-registered without restrictions or whether an additional practical driving test is required, for example.
Find more information here.