Cot to toddler bed

Hey mumma's when did youse move you child to a toddler bed? My son is currently 14 months old and expecting #2 in april 2017, so my son will be almost 2, now with buying stuff for baby #2 is it best to budget in a toddler bed for my first and reuse my sons cot for baby or should i buy a new cot and keep my son in his cot until he's almost 3? Im a FTM and don't know much about transitioning bedding etc... any advise would be helpful