Measuring progress of SEO projects depends on what KPI's are important to you. So, if you chose relevant keywords ranking, overall traffic and average session time as KPIs to track then the progress will be measured on their basis. As for the reporting I think anything less than a month is not worth reporting as minor changes happen in SEO on a day to day basis. So, I prefer to provide a monthly report regarding all the steps taken and the progress we make in that time period. Although, if you want frequent reporting then we can figure out a way as well.