Moving from tier to tier
How long do you usually attempt interventions on each tier before moving to the next one?
It really varies from school to school and district to district. Some districts and schools move on to the next tier after 2 weeks, others 6 months. I tend to carry out interventions on the longer side, especially with tier 2 and 3. I don't think I would ever recommend moving on after 2 weeks. That doesn't seem nearly long enough to shape a student's behaviors and patterns.
I usually ask the most resistant teachers to give each tier AT LEAST 6 weeks, but this is really a bare minimum and starting point in my mind.
This will also depend somewhat on the individual student as you get into tier 2 and 3.