One of my first jobs to assign is Clock Master (Maestro de Reloj). This job is especially important to do right away if I can't see the clock in my classroom while I'm facing the class, or if I don't really have a good handle on the bell schedule (as is the case this year as my school is renting me out to a neighboring district to put me at full-time... such is life working in a tiny district.)
Clock Master is my go-to when I need to know how many minutes are left in class. The first several weeks that's about the extent of the questioning he'll recieve (¿Cúantos minutos más?). Inevitably he'll answer in English and this is the main way they are exposed to numbers early on. Clock Master will soon be telling me the time, but only after having answered lots of yes/no questions about the time, one-word-answer questions, etc.
Clock Master serves teacher and class. Thanks Clock Master!