It depends on the OP's circumstances. If he/she acquired the citizenship through parents according to the Child Citizenship Act of 2000, then the OP can register to vote now because he/she is already a citizen and filing a N-600 is more like a formality. If the situation is more ambiguous and the OP was not sure about his/her own citizenship status at the time of filing the N-600, then I would recommend not to register to vote.
Ady, could you share with us how you would acquire the citizenship? If it is through your parents' naturalisation (while you were residing with them on Green Card), then you should already be a citizen even though the USCIS would like you to take the oath.
Disclaimer: please do not rely on my advice, as I am not an immigration lawyer and not well-versed in immigration matters. By claiming to be a US citizen, you do so at your own risk.