i put both my boys in beds at 2 years old. DS1 went to a toddler bed and DS2 went straight into a normal bed.
they mostly stayed in bed so it was never really a big issue. initially when they were first in there, we made a big deal about how they were such big boys which made it a bit exciting. on the odd occasion that they did get out, it was just a matter of consistently getting up, walking them to bed. not telling them, actually physically putting them in bed. they do get the message to stay there, DS2 was alot quicker to get it than DS1, maybe because he saw DS1 in his bed.
during the night, they get up occasionally and its the same thing, just take them back and say its night time.
sorry, no great advice, but i had the same concerns as you and it never really eventuated. just be consistent and dont make it like it punishment to go to bed, and if he does run out alot, try to stay calm and just keep taking him back, he'll get the message.