Yes, you should wait until you receive the refund from your original return. You also have to wait until the amended return form, Form 1040X, is available in TurboTax. That is currently expected to be available on February 28. Instructions for amending your 2018 return will be available when the form is available.
An amended return has to be filed on a special form, Form 1040X. It cannot be e-filed. You have to print it, sign it, and file it by mail. It takes the IRS up to 16 weeks to process an amended return.
