Only have 20 minutes a day—is it better to focus on phrases or grammar?

I’m a busy professional working full-time, and I only have a 20-minute window each day to dedicate to Irish. I’m feeling discouraged because my progress feels non-existent. Should I be using this time to drill prepositional pronouns and syntax rules to build a solid foundation, or should I spend the time on mobile apps just to get some daily exposure? Any advice on how to be efficient with such limited time would be appreciated.