It would be risky, unless you have everything prepared, the knot already tied and the noose around your neck firmly, and then take the other things. If you do it otherwise or left the hanging for last, you may not be able to ctb successfully, the clonazepam could make you incapable of tying the noose right or messing something else.
Another thing, if you take a little more of lithium than normal, you'll begin to have gastrointestinal symptoms, like vomiting and diarrhea, and it wouldn't be pleasant to choke on your vomit and literally shitting yourself while trying to ctb. If you survive, you'll have persistent health problems thanks to the lithium.