To qualify for CDP, your child must meet the qualifying periods conditions. There are two: the ‘backwards condition’ and the ‘forwards condition’. These conditions will not apply if your child is terminally ill (see 22 below ).
DACYP(S) Regs, reg 15(2)(a)

Backwards condition – Your child must pass the disability test(s) ( see 3 above ) throughout the 13 weeks before the claim. The claim can be made during this 13-week period, but payment will not start until the qualifying period has been served.
DACYP(S) Regs , regs 11(3)(a), 12(6)(a) & 13(10)(a)

Forwards condition – Your child must be likely to satisfy the disability test(s) throughout the 26 weeks after the claim.
DACYP(S) Regs , regs 11(3)(b), 12(6)(b) & 13(10)(b)