AWS EC2 snapshot reaches IOPS limit occasionally

For an EC2 server I have running I am creating a snapshot of the EBS every night. The EBS has 500GB of space and 1500 / 3000 IOPS. On some days past week the snapshot creating process reached it maximum IOPS causing the server to be unavailable for 5 minutes to an hour. What can I do to prevent the snapshot to use the maximum IOPS? I am creating the snapshot using https://github.com/CaseyLabs/aws-ec2-ebs-automatic-snapshot-bash