In the case of a claim under 508G before a specified individual commences a relevant employment with the company in which that individual has made a relevant investment (being that individual's first such investment), the relief shall be withdrawn if the specified individual fails to commence such employment -

(a) within the year of assessment in which the investment is made, or

(b) if later, within 6 months of the date of -

(i) where the investment consists of the subscription of only one amount for eligible shares, that subscription, or

(ii) where the investment consists of the subscription of more than one amount for eligible shares, the last such subscription.