SNP Planned Order Start date differs from ECC

Hi, We have an issue, where there's a difference in start date of SNP Planned Order compared to ECC.   On analysing, the Resource Consumption Fixed in SNP PDS it shows 288000 Seconds, which converts to 80 Hours

In ECC, the resoure is avialable for 8 Hours per day, so it needs 10 days, whereas in APO, SNP bucket capacity is 24 hours, so it takes only 4 days.

So the start date in ECC is 6 days earlier compared to APO. 

How can we correct this?  Can it be done via changing the behaviour of SNP PDS or when Saving the Heursitics?  Which BADI should be used to sort out this issue

Regards,

Bhavesh