Months. They tend to have a letter writing day once every other month. If they have received a letter since the last time they wrote, they write a response letter at that point. I typically send a letter each month, whether or not I have heard from my child. If I hear from them, I respond to their letter. But because of the lag in letters going back and forth, I continue to write in between to make sure they have the encouragement and knowledge that I have not forgotten them.
Bryce, thank you so much for writing to and encouraging your child through letters! Each letter makes a huge difference in lifting your child's spirits and confidence. It can take several weeks for your letter to reach your child, and then they will write back on the next scheduled letter writing day, which could be in a month or two. It can take anywhere between two to six months from when your last letter was sent to when their reply is delivered.