Get in in winter, makes everything so much easier.
plus will look crap for first few days anyhow so you don't want ppl to see it.
oh and research your tattoo parlor massively, as remember they are "permanent".
(permanent in so much that they are very painful to remove and leave a scar)
and I would say the fact you are still unsure what you want means you should prob not get it, you don;t want to walk in and pick something out of a book, you want to go in with a design and be telling the guys exactly what you want.