Why not start with Homeland? It has incest and demon sex. Giant lizards and lots of killing. Basically, why jump in on the third in a series? The first kinda established what drow society was like.
Because of film making logistics you have to often make certain sacrifices when translating a novel or comic book to the big screen. Why not start with
Homeland? Several reasons.
1) Both
Homeland and
Exile take place almost completely in the lightless Underdark. Denezens of The Underdark see everything in the infrared spectrum. It would be very difficult, time consuming, and costly to present this on screen in post production. Not impossible, mind you, but difficult, time consuming, and costly.
2) Most of your average movie goers have niether played D&D nor ever read any of the Drizzt Do'Urden novels. As such, they would likely find the scenes done in "infravision" confusing and possibly hard on the eyes. As about 90% of those first two stories take place in infravision, that's not a reaction you want from your audience.
3) With proper writing and directing, making the first two books into movies would be unnecessary. A well written and filmed prologue explaining Drizzt's life up to the beginning of
Sojourn (like the one at the beginning of
The Fellowship Of The Ring), in addition to a well written and directed scene of Drizzt telling his life story to Mooshie, makes up for the lack of the first two thirds of the trilogy and provides the uninitiated with the background information they need.
4) You don't have to start a story at the beginning for a movie to be successful. Anybody remember a little film called
Star Wars? It began in the middle with Episode IV, and went on to become one of the most successful films of all time. The Drizzt franchise began with
The Chrystal Shard, and went on to become one of the most successful fantasy stories of all time. Starting the series with
Sojourn won't hurt the chances of success, but would very likely increase those chances.
5) Starting the movies the same way the books were started, with
The Chrystal Shard, is also a bad idea. The uninitiated will have no idea why Drizzt is so feared and dispised by so many, even though he's clearly undeserving of such scorn. They may mistakenly believe Drizzt is meant as some sort of social commentary about racism and intolerance or something. Starting with Sojourn relieves this confusion, without adding any more.
6) You can always go back and make the prequels. Hell,
The Dark Elf Trilogy itself is a prequel.