Thereu2019s no rule as long as you are back before your travel authorization expires. So theoretically, you can leave and be gone continuously until the expiration date on the advance parole documentu2014but if you are waiting for an interview on your adjustment, you canu2019t get interviewed until you are back in the United States. Being gone for nine months will likely delay approval of your green card. Be sure to come back before the advance parole document expires. You may also need to get a new A/P if your adjustment is delayedu2014and it can take three months to get a new A/P document. If your spouse is not going with you on this long trip, you should also be prepared to prove that this is a u201cbona fideu201d relationshipu2014the extended separation may cause USCIS to question whether you intend to have a life together with your spouse.