As a beginner, or when learning any new material, you can keep your practice sessions short. Just 5-10 minutes a day is perfectly adequate for building new skills.
That said, practice as regularly as you can. Every day is ideal, but 4-5 days a week will work, too. I recommend attaching it to some other regular daily habit if you can.
Warm up with exercises that work just one layer of music-making: for example, practice any new chords with Ready-Set-Go on your left hand, or strum along to a song or video without singing or chording.
Finally, don’t underestimate practicing without your instrument, wh
ether as part of your practice, or in moments of your everyday life. The most helpful exercises in these instances are: 1) visualize your chord changes and/or move your left hand like you would if you had your instrument; and 2) audiate (sing in your head) the songs you’re learning. While these skills / exercises don’t take the place of practice, they can help keep your brain thinking about it between practice sessions and help you develop other skills more quickly.