New car on order - Build week question

Hello,

I have ordered a NConnecta Xtronic in Magnetic blue in Jan though a leasing company, it is a factory order but I'm being told there is no build week yet assigned to my vehicle, but they are chasing nissan regularly for updates.

When I ordered they estimated it should be delivered sometime in April, but I'm beginning to get concerned that there is no build date yet and only 2 months to go.

Does anybody know when or how the build weeks are assigned to new vehicle orders at the factory?

I'm sure I read somewhere online it's approx 4 weeks before build that the build week is assigned but can't seem to find the post now. Im in the UK so once built I wouldn't expect it to take long to go to the dealer (no waiting for a ship etc..)

Any insight anyone can give on how the Nissan ordering process works would be appreciated.

Thanks