Setting - Irritating people present for a first time trip?

[metrik]

SWIM had a dream in which he had wanted to try LSD for a couple of years but previously hadn't been able to get a hold of any, but now he could.

However he had a reservation which he was looking for advice about. He was planning on taking it with his two housemates, one of which has tried LSD a few times before, both he and the other housemate have had a few experiences with mushrooms but also want to treat the LSD trip with respect due to what they have read and been told. The problem is one of the housemates girlfriends also wants to be in on the trip, this is a problem because the girlfriend is often very loud and in peoples faces and generally wasn't considered to be the kind of person SWIM would like to trip with for his first time. As well as being very loud and at times irritating she also doesnt seem to know anything about the drug and talks about it as if its no big deal at all, this gave SWIM the impression that maybe she doesn't realise what she might be in for and could be overwhelmed, she has had bad experiences with other drugs fairly often due to not knowing her own limits and acting macho with drugs such as 'trying to keep up with others' and such instead of just taking things at her own pace.

In SWIM's dream he was wanting to know what other people would consider the best thing to do, he considered he could tell his friend about his reservations but this may cause awkwardness in the friendship and his friendship with the girlfriend, he could not partake in the experience and wait for another time though it feels like this is the time we have been waiting for and would feel a little 'robbed' to stay out of it now.
What would you recommend?

Also if SWIM goes ahead with his trip he also dreamt about whether it would be prudent to drop half and wait for those effects to kick in before dropping the other half as opposed to taking a whole tab in one. What would you recommend for SWIM's first time?