No, the date of the original test is when you start your 2 years probation. The overall licence "from" always takes the date of the last added category. You'll see on the back it will have the from and too dates of each category. It makes sense if you think about it, ie the particular licence you have showing your current entitlement is valid from the dat of the last category update. Eh if you passed your bike test tomorrow then the licence to get back would run from tomorrow.