Not all 335DWs can be accepted as their unit might not be suitable due to canal size and shape, or condition of the shells. The existing units have to be brought to fitear directly.
As fitear has to open the faceplates to do the upgrades, some blemishes might occur. Also please understand that the SQ is a leap of faith.
Upgrade takes 2-3 weeks. Units with older faceplates will have it replaced with new ones at addition cost. 52,500yen vs 42,000yen for those with newer faceplates.