If you mean that you registered for VAT in October 2006 and then purchased the van in May 2007, then provided you have a valid VAT invoice from the supplier showing that VAT was charged to you then you would be entitled to a VAT input credit for the purchase.
Bear in mind that to be entitled to 100% VAT credit then there must be no non-business use of the van, e.g. you must have other personal transport. If you do not have any other personal transport then some apportionment of the VAT must be made to only claim that fairly used for business purposes.
Also, if the van was purchased straight ( for cash/cheque ) or by bank loan or HP then the VAT is claimable in one go. If it was purchased on lease, then the VAT is claimable with each payment, so you'd have two instalments per bi-monthly VAT period.