my question is can I leave SG before they print out the notification letter, or do I stay until they print out the notification letter and email to me, so that I can leave SG with the notification letter.
You can.
I get my EP this month only, I travel daily in and out to work. Does this calm you?
Ok, white card got 2 portion, lets say 1A and 1B
Example:
22/7 you go in Singapore with 1A+1B, they take away your 1A, return you 1B
22/7 you give your company to photocopy 1B, then they use your 1B detail to register for appointment letter (In this case, I am assuming you got your IPA way earlier)
22/7 you get reply that your appointment with ESPC will be on 26/7, for fingerprint verification etc etc.
22/7 PM, you back to Malaysia, 1B was taken away by immegresen (else how you leave SG?)
23/7 you go in SG to work with 2A+2B, back Malaysia and give them your 2B
24/7 3A+3B, 3B return when u back
25/7 4A+4B....
26/7 5A+5B, you bring your 5B white card portion to ESPC, just let them know that because you are travelling in and out daily, so your white card detail is changing daily. After all the verification bla bla bla, they will tell you to collect your EP on... say 31/7, then they will chop on your e appointment letter, stated in progress, then staple your 5B white card on the letter too
26/7 PM you get out SG by showing immegresen your letter and the white card 5B,
this time they will NOT collect your 5B29/7 you go in SG with letter and white card 5B, you back MY with letter and white card 5B
30/7 same as 29/7
31/7 Go to ESPC and collect your EP, you need to give them the letter and card 5B
31/7 PM you get out with your EP and say bye bye to white card for next 1-2 years.
Hope above explain well. You are lucky that I am in good mood to type so lengthy, haha!

wrong info. They will collect your 5B card and issue you the notification letter only with a stamp on it stating which date you will collect your EP.
That piece of paper will serve as your EP and u just need to attach it to your passport and you can enter and leave as many times as you like.