i wanted to know the approximate time from any of the applicant who recently received the result.
After receiving file, Singapore first open the file, note down all the information, check all the forms. If everything is ready than it goes for review by a visa officer. Visa offier will take the decission whether your relationship is genuine or not. If he is satisfied that the sponsored person is a member of Familly class, then it will be written as "Eligibility: Passed". So you don't need any interview at this stage. But they have right for interview any time during the whole processing time. At this stage Singapore updates the ECAS status as "In Process". The date they say started the processing is actually is the date VO takes the decission Eligibilty Passed. I found this in my GCMS notes. I think that's why all people who see In Process do not require to attend interview.
I am not sure exactly when they start security and criminality check. But I am sure Singapore asks for passport after getting these clearence. It varies from person to person. I heard normal check takes avg 3 months.
Singapore asks for passport at the end of processing where as some other visa office like New dellhi asks at the beginning.
Whatever I am saying here is completely based on the cases I have read here and my experience with Singapore. So May be I am not 100% right.