At my home town Kuching there is a postlaju branch at Petronas station, they receive parcel during Saturday, means that you can post your item on Saturday. But I dont know whether they will send it out or just keep it in their office until Monday.
But when I send parcel from Penang on Thursday or Friday, normally my frens / receiver at Kuching will receive it on Saturday afternoon. They will deliver it on Saturday also.. I've been using postlaju for years.

I dont know the other place like KL is the same or not..