Monitoring means comparing actual progress against the plan at regular intervals -- weekly or biweekly for most projects -- rather than waiting until the deadline to discover a problem. Useful KPIs include percentage of milestones completed on time, budget spent versus budget planned, and number of open risks or issues; simple is better than elaborate, since a KPI nobody understands won't get used. A good status report answers three questions concisely: what was accomplished since the last update, what is planned next, and what risks or blockers need attention -- typically fitting on one page. Catching a schedule slip two weeks in is far cheaper to fix than discovering it the week before delivery.