How should i proceed

My gf of 3 years and i were discussing bringing in a third person in the bedroom we decided it would be a male the first time
but since we decided that we haven't talked about it since i don't know how to bring it up without looking to eager any tips
do it when it feels natural. usually over drinks at a bar or something where there is a good looking guy you can get her to check out. start a conversation about if she finds him attractive or not. what she likes. then ask is that the kind of guy you would want to be the third? or did you have something else in mind? if you are calm about it she will be as well. she also may say she really doesn't want to do it after all when it get too real.
 
do it when it feels natural. usually over drinks at a bar or something where there is a good looking guy you can get her to check out. start a conversation about if she finds him attractive or not. what she likes. then ask is that the kind of guy you would want to be the third? or did you have something else in mind? if you are calm about it she will be as well. she also may say she really doesn't want to do it after all when it get too real.
we dont go to bars or clubs any ideas how to bring it up at home
 
we haven't talked about it since i don't know how to bring it up
Has there been any movement on this? My suggestion would be 1] some time when her spirits are high and there's nothing pressuring her or demanding her time or attention. And 2] there's always special days -- holidays, vacations, Christmas, a birthday, a weekend getaway for that purpose, That sort of thing.