Well done nicchick. Sounds like you've cracked it.
On the subject of separation vs let-them-get-on-with-it, there's no right answer in my opinion.
The first thing you have to take into consideration is personality. You know your cats, and most people can make a reasonable guess at the personality of the new cat. So if either cat is shy or takes longer to make friends, take things at a more gentle pace.
If they are both the sort that looks for a crowd to join in, can start a conversation with anybody, and has a bright extroverted personality, then why not let them get on with it.
The other thing to consider is space. No matter what the personality, if you force them into the same small space which at least one cat believes is theirs and theirs alone, there will be trouble. If they are outdoor cats and can disappear for a bit of "me time" there is less potential for bother.
Use your judgement. If we didn't have it we would keep hamsters, not cats!