First of all, it's not “at least 90 days”; it's within 90 days. So it could be 40 days or it could be the first week.
Again, I can only speak for Ontario, but at Millhaven Institution, they have a mental health unit. If there's someone who, on intake, is having difficulties and that's noticed right away, then that person can be taken out of the general population and put on the mental health unit while he's going through the intake assessment process. The officers on the intake unit are watching for those sorts of things. There are mental health staff who work on the intake unit and are available to intervene with offenders when it's needed.
The guidelines say it's within 90 days, but some people are identified immediately on intake. They say “This is a guy with mental health problems and we need to address it”. There's a psychiatrist who goes to the assessment unit and is able to prescribe medication. If they need immediate intervention, they're identified and sent to us at the treatment centre.