Exactly 7 years between my DDs (fertility issues)
Dd1 wasn't remotely interested in her, until she was at least 5 I would say. She just pretty much ignored her (not in a nasty way)
She was just one of those children who wasn't a bit interested in babies.
She didn't like, nor dislike her, there was no jealousy.
They are 7 & 14 now (so dd2 is now the same age as dd1 was when she was born) and they're very, very close, despite the age gap. Dd2 worships her, and pretends (or genuinely is) to be interested in everything dd1 is into, clothes (primark), music, sport etc.
DD2 was 2 when DS arrived, and the only difference is that they are/were playmates. DDs missed out on that together.
But the bigger age gap was much, much easier for me, and is narrowing all the time as they get older.
In summary: I'd say it depends on your child's personality, and how they feel about babies, or being an only ((dd was very happy to be an only child)