I do not recommend a GEBO Rune work or an actual love spell for three main reasons. These three reasons are related to the fact that, since you don't know her well enough *considering you said you just dated, you may not have developed true romantic love for her yet. So, if you do a love spell, 1) it will be unethical because if it doesn't work well between you, you would only make her suffer 2) You would consume a lot of energy and time even though she may not be the right one 3) It could be annoying to make fall in love a girl who could then turn out to be impregnably obsessive towards you.
Since we are Satanists and we value responsibility, a love spell is not what you need here. Rather, one thing that might be useful for increasing your relationship is a magical work with the Wunjo Rune (try the Vin variation, I'm comfortable with that).
You might also consider programming your aura to be extremely pleasant to her. However, I highly doubt that the right choice is a "love spell". Love is built slowly and you cannot go from 0 to 100 "love points" just after a few outings. When the relationship has consolidated, you will then decide responsibly whether to carry out work on her with GEBO.
Obviously, since you haven't given too much information about your current relationship with her, you will have to establish when what I have described is your specific case and corresponds to your current situation with her.
Anyway Yes; esbat in Sagittarius is ideal.