When should I pursue a divorce? Before, during or after deployment?

Your best course of action would be to speak to a lawyer familiar with family law. Divorces that happen while on active duty are handled a bit differently than those that occur when you're not (or rather, they COULD be handled differently as other laws could come to bear).

The Wyoming Military Department provides access to Soldier & Family Readiness Specialists* which appears to allow you to tap into these services provided to WYARNG Soldiers.

Additionally, if you have pre-activation orders (sometimes called 'delayed effective date' orders), you MAY be eligible for legal assistance as if you were an active duty Soldier (i.e., free legal advice). You may be able to tap into the 90th Missile Wing Legal Assistance at Warren AFB* as they are the closest legal assistance to you.

Finally, if all else fails (or, you can start with them, you can hardly go wrong using them as your first call), call Military OneSource [login to see] ) and talk to one of the counselors there and they can route you to someone that can assist (if you're eligible).
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* WYMD S&FRS - https://www.wyomilitary.wyo.gov/resources/family-programs-3/soldier-and-family-readiness-specialists/
* 90th MW/JA - 6307 Randall Ave. Suite 209 [Bldg 232], Cheyenne, WY 82005, Phone: [login to see] (other locations can be found using the Armed Forces Legal Assistance locator - https://legalassistance.law.af.mil/)

I would advise you to ask legal questions in a private forum and not somewhere where your question/answer could be used against you in family court. (not an attorney)

I will give you a bit of advice. First, if you want to get divorced get it ASAP. Do not wait for year. When you are on active duty you will be required to pay your separated spouse IAW AR 608-99. As soon as your spouse speaks to a lawyer they will find out things like this. It gives the spouse the ability to pay the lawyer. If possible you can ask your spouse if she willing to divorce and the both of you can come to an agreement and settle things. This will save you time and money. I would not wait on the deployment to get the divorce. I have never met anyone that was glad they waited to get a divorce. I can tell you from experience my regret is that I didn't act fast enough.