Bundles are valid for one month starting on the top-up date. If you have an active discount bundle from a previous top-up, it remains valid for one month after your top-up is active, even when you top up after 11/1/2018. A practical example: if I top up for € 10 on 20/12/2017, my bundles from this top-up are valid until 20/1/2018. Do I top up again for € 10 on 12/1/2018? If so, nothing changes for the bundles that are valid until 20/1/2018.
On 11/1/2018, you will be automatically switched over to the new rate plan. From then on, you will only receive free calling minutes on JIM Mobile and no additional MBs or (unlimited) texting with each top up.