Depends on your tolerance. If you do them both regularly then you can do them together. If it's your first time though, make sure you don't have any responsibilities to worry about, just in case.
I used to snort Klonopin with Heroin. I snorted a tiny bit before work like a fucking moron and fell asleep at the wheel of a van with 5 people in it and almost killed us all. It took me hitting the medium on the freeway to wake up. Popped a tire, slowly crossed all lanes of traffic where some cops were waiting. I told everyone with me that the story is the tire popped which caused the accident. Luckily no one got hurt and I didn't get arrested.