L.,
I transitioned my oldest two children from a crib into a bed at 16-17 months. I intended to keep them in the crib longer, but my daughter climbed out and I got a "no lifting" order from my doctor with my son, so we didn't have a lot of options. My third child is at this age now and because he shares his room with his sister and there isn't a need to move him out of his crib, I am going to keep him there for another 6 months.
It is very possible to transition your son at this time. We put our daughter in a regular twin sized bed and put down a lot of pillows on the floor. She rolled out a few times and learned not to. We transitioned our son to a toddler bed (he is 3 and still there because his bedroom is so small.) Again, he rolled out a couple of times and caught on.
My best advice is to set up his room ahead of time so he will go to sleep there. Pick up everything he could play with and put it up high, lock it up or get it out. We took the knobs off the dresser and put the bookcase in the closet with a lock on the door. Do something to the bedroom door so your child cannot get out. If you want the door open, use a baby gate. You can also use a child safety lock. If you are concerned about a safety hazard, take the lock off after your child is sound asleep. Our children learn to use those quickly, so we took the doorknob off and turned it around so that the door locks from the outside of the room. (This also kept our children from locking themselves in the room.) If you do this, make sure to keep a key or something up high to pick the lock if your child locks you in the room.
Put the child to bed like you normally do and leave the room. Don't go back in and keep checking to see if he is in bed. You can expect that he may get out of bed and wander around for a while. Put him to bed early for several nights to compensate for this. Sooner or later, especially if there is nothing to do, he will get bored and tired and lay down. It is not uncommon for them to go sleep on the floor by the door for a while. Don't get discouraged. Just give it time. If he is a heavy sleeper, put him in his bed when he is asleep so he learns to wake up there.
If you want to do this before daycare starts, do it tonight. Don't spring two major changes on him at once. It is helpful to the daycare staff if your child already knows how to stay on a mat, but they can train him because they have done it before. If you can't make the change tonight, wait until he is settled in at daycare.
Best of luck,
S.