A legal separation does not have the built in three month required waiting period so if you have all the documents ready you can file and finalize the right after. An attorney could do it rather quickly if it is simple. This is without children. If there are children you have to complete the court ordered parenting class before you can finalize.
NOTE: this answer is given on a limited factual basis and does not constitute legal advice. It is advised that you seek legal counsel or consult with an attorney. www.tamblynlaw.com
There can be legal problems if you both just want one attorney to do the divorce for you in the end. If you guys really are in agreement and just want someone to double check your documents, one of you could "hire" an attorney and the other one could go pro se with the idea that if anything is changed the non represented party would not agree.
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