here's my experience from a total newbie about cats getting along lol. my bf and i moved in together, he brought his 14 yr old DSH, Forest. Forest seemed bored and started getting fat (was an outdoor cat at his old home). So I came across bengals and wanted one and thought "what a great playmate for Forest".
Turns out not so much, at first. When we brought Gizmo home for the first time, we just let him out of the carrier thinking everything would be fine and dandy. (had NO idea about seperating him for forest to get a smell of someone new) WRONG! hissing and spitting and swatting for the first few days, and gizmo hiding for 3 weeks and forest peeing almost everywhere...
after a month or so, they started playing but more of it was fighting. forest still peeing and gizmo still hiding but coming out to feed and play. got gizmo neutered after a month of having him when we realized he started spraying things. that seemed to calm him right down.
at about the 3 month mark, things started to settle down and not much chaos.
it is now at the 4 month mark and forest is now licking gizmo before they play. gizmo thinks he can eat first and forest obliges lol they watch video catnip together. play with da bird together.
we are finally relieved having a peaceful home with 2 cats. i think the major factor was forest being an only child for 14 years. and then this newcomer just barges in (our fault really), into his home.
hope that helped a bit
but the way i read your initial post it sounds like both cats are coming from the same shelter, so i would assume that they already know each other?