It may not look good for you to leave your NCOER unsigned. I would encourage you to ask your command to delay submission of your report until you are available to sign. They have significant time to complete the report as the report is not due at HQDA until 90 days after the thru date: see AR 623-3 para 1-4 b(15). You might want to ask them if they would like it if their report was sent forward without their signature. If you are an E-5, the impact on your record will most likely be minimal. If you are a SSG or above it could have a significant impact on your career.