I applied in 2171. I was working with a consultant for FSW2014, but missed the cap so they managed my SINP application. So I was not hands on on the SINP side, but once nominated I did all the rest on my own with extensive research on this forum and the CIC (IRCC) website.
Basically the profile was created and kept ready, and as soon as it opened, they submitted it. Back in Nov. 2015, I am not sure if it was not demand driven. The OID stream was demand driven, and EE stream was separate.
You should create an application on Oasis (SINP's application portal) and keep it ready, and as soon as it opens, submit it. The only thing you will need to update is your bank statements every month as they expect previous 3 months at the time of submission.
Hope this helps