Gather 80 sand and 80 fire to craft 80 glass (it'll take 8 hours to craft each glass), and after gathering 80 firefly (you can drop any villager on them to collect the firefly, and they can be found flying around your village), combine the firefly with the glass to craft holiday light (it'll take 45 minutes to craft each one). I don't know how long it'll take, but the limit is 17 days, so spend your lavastones at your own judgement.