First time questions

I was finally able to get my hand on some ketamine after long time of searching, I just have some questions before going into it. What to expect ? I mean what does the headspace feels like? (I have experiences with coke, lsd, mdma) Also, is it okay to mix with weed? Last and most important, i am diagnosed with generalized anxiety i would like to knw if some people experience anxiety and panic attacks on their first time or the effect helps you stay calm?