Decide when and how long you will do calendar time.
A lot of this will be based on how much time you have. My classes are only 25 min and our full calendar routine can take up to 7-10 minutes.
During a unit where one of the elements is part of calendar time then we take the time and do it every class or every other class. When it is not part of our unit of study then we do it only once a month (so that students don't forget the different elements.)
If you have 50-60 minute classes then you might consider doing calendar time every class period.
Decide what your routine will look and sound like.
I love teaching with music. I introduce the following songs one at a time as we build up our calendar routine. Once the students have learned the song I stop showing the video and we sing a cappella.
We go over the days of the week using this song from Basho and Friends. We dance the macarena as we sing. Then we do Hoy es... Mañana será... Ayer fue...
I use Calico Spanish's song Meses del Año to practice the months. Then we talk about what month it is and count up to the date.
We don't sing a seasons song during our calendar time but I did use these videos from Calico Spanish and Basho and Friends to introduce the vocabulary. Once they knew it, I just ask students what season we are in.
We sing this song from Super Simple Spanish to practice the weather. Then students talk with a partner about what the weather is that day. After a few seconds I look it up on my phone (I'm in a windowless room!) I call on a few students, and then we move the area on our weather chart to the weather of the day. Most days we also guess the weather in Mexico and another Spanish speaking country (usually in the southern hemisphere so students start to understand that the seasons are opposite there.)
Then we dress the weather bear. Like with the seasons we don't sing the song once students know the vocabulary but Calico Spanish has a great one to introduce clothing. I like it because it also has the seasons. I usually give students an either/or choice and they tell me what I should put on the bear.
You can get your copy of the weather bear and his clothes in my Teachers Pay Teachers store here. In addition to using it during calendar time you can also print them out as paper dolls. Or laminate and put magnets on them and have students play with it on cookie sheets.
Keep your students engaged and accountable.
My goal for the last part of this year is to implement calendar pages with students. My students already love calendar time but this will help those students whose attentions wander and get in some writing practice. My plan is to put them in sheet protectors so they can be used over and over. The first graders will use the simpler one below and I have another one with months and seasons for 2nd graders. You can get your copy here - it's included in my Weather Bear Activity Pack! For an assessment I'm thinking I'll make smaller paper copies and have students fill them out and turn them in every once in awhile to track students' progress.