The every three weeks schedule is one choice in a 70/30 physical custody schedule. Your child will spend two weeks with one parent and the third week with the other.
Below is a visual calendar of the every three weeks schedule made on the Custody X Change software. Time with the mother is represented in pink and the father blue.

This schedule is very consistent and easy to implement. Your child is able to spend longer periods at each home and not have a lot of disruptions in their life. Children who like to have longer times at each home find this schedule comforting. Parents who also are still having conflict find this schedule to work well because of the limited exchanges. You will have to communicate frequently with the other parent about what is happening in the child's life.
The main issue with this type of schedule is the age of your child. You want to make sure they can handle being away from one parent so long. Some parents also find it difficult to be away from their child as well. You will both need to live in the same school district if your child is school age.
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There are many ways you can change the every 3 weeks schedule work for you. Below are some different examples of how we have changed the schedule to meet different needs.
This first schedule has the mother with two weeks and the father with the third. There is also one night where the child spends time with the non-custodial parent. It is a great way for you and your child to spend time together when not in your home.

This second example is has changes the exchange time to Sunday instead of Friday.

Creating an every three weeks schedule using Custody X Change is very simple.
First, download and install the free trial.
Next, click on the first tab, "Regular Schedule" and you will see a calendar. To the right of the calendar is a menu of all the different custody schedules or the ability to create your own. Under the 70/30 title, select Every 3 weeks.
The calendar will automatically fill out for you. You can now make any needed changes. Watch the video tutorial for additional information on creating a custody schedule.
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