I had to go back at 8 weeks. My dd had bottles from day 1 (thanks to jaundice and a crappy pediatrician and hospital staff) so we knew that wouldn't be an issue. You will want to start your lo on bottles a week or two before going back. If it's family that your lo will be staying with, make sure they know that a breastfed baby shouldn't be allowed to chug a bottle and how to "pace" them. My daughter was fed 12 oz in 5 hours my first day back because they just didn't know how the difference between breast and bottle meant that she would take so much more. It also helped me to have sort of set times for pumping. I noticed that if I was even 30 minutes early one day, I got less that day. It was like my body learned to expect it. I don't know if that's normal, but it definitely happened to me. The other big problem I had was getting busy at work and not drinking enough, therefore pumping less. Really watching my liquids was huge.
Everyone told me to work on a freezer stash, and that's not a bad idea, but I didn't understand that I couldn't just rely on it if I had a day that I got less. If you're pulling from your freezer stash, that's that much less your telling your body you need, which does end up decreasing your supply if you make it a habit. You probably already know that, and I did once I thought about it, but it didn't really register to me when I first went back.
I hope something in all of this is at least a little bit helpful.