From the instructions for Schedule SE

"Changing Your Method

You can change the method used to figure your net earnings from self-employment after you file your return. That is, you can change from the regular to the optional method or from the optional to the regular method. To do this, file Form 1040-X."

Before you venture too far, consider the cost of the SE vs the EIC. This can also have a long term benefit in accruing Social Security quarters.