I can cover expenses like tens of thousands of dollars for marketing. But why should I do it before finding a distributor?
I just don't want to start spending with an unknown release date. And how do you think people like Oren Peli did? Did they spent millions for marketing right after they have completed their 15.000 dollars budget movies?
First, don't take offense to this, but everyone thinks their baby is the most beautiful baby in the world. It's the same for most film makers. I do hope for your sake that you're correct in saying your movie is good. That's a decent start. The problem is there are probably 500 good movies out this year. How do you rise above them? By not being good. You need to be better than great. You have to be the best. Are you the best?
The honest answer is, you don't need to spend tens of thousands on marketing...... so long as you have the other essential marketing elements in play and have a distributor willing to spend the required money necessary to make your film a success. Which primarily means a marketable A-lister (or up and coming A-lister) attached to your feature.
Though, in this case, I suspect you don't, hence why you're here.
One thing you have to be aware of, distribution rarely has anything to do with how good the movie is. I really wish it wasn't that way, and there can be some occasional runaway successes that break the mold, so all hope isn't broken. To understand the basics of distribution, you also need to understand that distribution is a marketing exercise. It's all about getting bums in seats and the cost/benefit ratio of that exercise. You're essentially asking someone to gamble $25mil on your film. Would you do a $25mil gamble on a good movie or would you wait for a great or the best movie?
Bring back to Oren Peli. Now how I understand it, he (and his team) did a rather aggressive social media campaign to significantly raise the profile of Paranormal Activity before it hit the Festival Circuit. This brought a mostly (in my opinion) boring film and managed to turn it into the seeds that ended up being a franchise capable of delivering 9 digit box office numbers.
Truth to the matter, you're a little too late to be asking these questions. Distribution should be something you're considering and conversing with distributors in the development phase. "Is a movie doing this, with this and that something you're interested in?" and so on.
At this point in time, you're probably best off making sure your film is the best film made this year. There is a lot of competition too. I've heard the number of 5000 being thrown around as the number of feature films being made this year. That's a lot of competition. That's about 15 a day. Most of them are never going to see any worthwhile distribution. The only way to rise above all that is to be in the top .1% especially if you have no star power.
Of course this all depends on your goals with the film. I'm assuming you're hoping to get a wide cinematic distribution deal and to be able to bank a serious chunk of change into your bank account. If your goals are more modest to perhaps find someone willing to pick up your film for DVD or VOD distribution and earn you somewhere in the 6 figure range, you may be in for a pleasant surprise.
There is a product you can buy to help you understand more about distribution and the situation you're in. It costs $600 (I see it's on special this month for $540). You can find it here:
http://www.distribution.la/. I have nothing to do with Jerome and I get no kickbacks from this recommendation. Take it or leave it. I did his course maybe 6 months ago. While it's not the be all of distribution, it really excels and is probably the only course I've seen that will help you get out of the situation you've got yourself into, an independent filmmaker who has a film but no distribution. It'll also help you develop a plan to turn that festival circuit plan you have into a distribution deal you can live with.
Good luck. Let us know how you go.