If the original return shows a refund due, you should wait until the refund is received before filing the amended return, even if it results in an additional refund. If the amended return will result in additional tax due, you should file it as soon as possible, and you can file it even it's before the original due date.
If the original return shows a refund due, you should wait until the refund is received before filing the amended return, even if it results in an additional refund. If the amended return will result in additional tax due, you should file it as soon as possible, and you can file it even it's before the original due date.