There's a book by Ferber called 'Solve your child's sleep problems' that explains lots of problems and how to resolve them. The number one being the child not knowing how to fall asleep on his/her own. It recommends that you follow a soothing routine that helps the child make the transition but that you put them in bed when they're fully awake. It then also recommends that if they cry, you check back after 5 min. and wait progressively longer (5 more min each time.) I have 3 kids, and on the worst night it seemed like 45 min. was the max that it took with the time progressively shorter each time.
I did this with my first when he was 4 months old, and the results were phenomenal.....he's been my best sleeper ever since. It took 3 nights with a max. crying of 20 min. the first night. Of course, that was the longest 20 minutes of my life!!!! The 4th night he just went to sleep and never had a problem again.
With my second I was more careful not to establish poor sleep habits from the start, but I did occasionally lapse into bad habits (it's really hard to not let an infant fall asleep blissfully while they're nursing), so I had to let her cry a couple times but never had to do any major intervention.
With my 3rd (now 20 months), I was actually the worst about this, and he has the worst sleep habits. We had a nightmare visit with some relatives over the Christmas Holidays when he woke us and the rest of the house (including young cousins) up repeatedly for multiple nights, and after that, we decided we needed to break our bad habits. Given that he was about 16 months by that point, it took more probably a week to get him to go to sleep without crying and then probably another week until the benefit carried over to no waking at night.
Net, I'd recommend that you do it while he's young....it's awful but still easier than when they're older (and you'll be getting sleep between now and then.)
I personally would do it now because I think it'd be great to go on vacation with this problem behind you. I do seem to recall that the book recommends that if you have a vacation coming up within 3 weeks you wait until after you return given that vacation also messes up sleep habits.
Anyway, best of luck....it's one of the hardest things to do and it's gut-wrenching to listen to a baby cry for even a few minutes when you know you could comfort them, it really only takes a few days of sticking with it, and in return the whole family gets a lifetime of good sleep.