First, welcome to the Church!
As a kid in the 50’s I was taught to do so. It is a reminder of our baptism, and a (very) short confession of it.
It was said, in another thread, that one (might not) (should not) do so upon exiting, particularly if one has just attended Mass, as one has not only done so at the beginning, but confirmed that baptism by participation in the Mass.
However, assuming that to be correct (if makes sense, but again is not what I was taught long ago), one can rest assured that there are no liturgy police hovering around the font to determine if you did, or did not, cross yourself upon exiting. Think it through, and determine what you wish to do. You won’t be graded.
First, words are important, and this is one of my pet peeves. One receives; one does not take. Not your fault, certainly, and all too many people say “take”. I can’t figure where that came from; back in the day we would have had our ears boxed by the good sister had we said that. As an aside, it comes from a specific; in a Mass, the priest takes the Host and receives, and if you attend a concelebrated Mass, the priest will take the ciborium and let each of the other priests take a Host from it (or alternatively, they will approach the altar and take one as the ciborium sits there). No one else - deacon, Extraordinary Minister of Holy Communion or anyone else is permitted to take a Host and receive it;it is handed to them or placed on their tongue.
Having said that, no, I do not genuflect after receiving and returning to the pew (and we did not do so in the 50’s). As noted, you have received Christ.
Additionally, should you whip around and go down on one knee, you are apt to have the person behind you run smack dab into you as no one is expecting the person in front of them to do so.
I kneel. The question was posed to Rome several years ago about what posture we are to take upon returning to the pew. Rome’s answer was we could stand, kneel, or sit. Most parishes I have been to, they kneel. A (very) few have some standing (it is disconcerting, but within the law) and some occasionally sit. Your choice; but if you are out of sync with others, someone likely will ask why you do so, or tell you that the “law says…” and likely as not they are wrong. And usually, they are doing so because they don’t like anything different from what they believe is the “right” way.
No one let them in on the really big secret: if you put your head down, and maybe put your face into your hands, you won’t see what others are doing, and if you don’t see it, you should not be bothered by it. #thingsmymothertaughtme
If I am doing so during Mass, I bow to the altar. If it is before Mass, or after, and I am moving from one side of the Church to the other I genuflect; however, my knees are getting older than my mind and they are becoming a bit obnoxious. That may or may not be the exact law; but the point is to give honor to the presence of the Blessed Sacrament and both do.