There isn't a fixed amount of time that it takes to complete Up Learn, because it adapts to give you more or less learning/practice depending on your ability.
It's great to start early on in the year as this gives you more time to practice and makes it easier to recall what you've learnt in the exam. Saying that, it is never too late to start! Using Up Learn is the most effective way to spend your time in the lead up to your exam and any work done will still have a big impact on your grade.
If you’ve already covered lots of content at school, you should be able to work through the earlier parts of the course fairly quickly. The course adapts to take into account how long it is until your exam, and will direct you to the area of the course that is the most effective section for you to study.
Generally we say that it takes approximately 12-15 weeks to complete an Up Learn course from scratch when studying for 5-7 hours per week. Some courses are longer or shorter depending on the exact A Level specification.
Even if your exam is only a week away, jumping on Up Learn to complete some practice papers and clarify any last minute topics will be extremely valuable.