The big bed
The move to the big boy/girl bed is a daunting one. I can happen anytime between 18 months and 3 years. There is no specific time for this change, but most parents make the swap once their little one is able to climb out of their cot. Once you change out for a bed your toddler can get out of bed at any time throughout the night, so if you haven't already, ensure their bedroom is thoroughly child-proofed. If you are working on staying dry overnight, the swap to a bed means your little one can get up for the toilet in the night.
The transition can be tricky for a toddler so make sure you don't change this up during a time of disruption anyway - for example when having another baby. Taking the blanket from your toddler's cot into the big bed can help ease this transition for some familiarity.
Letting your little one pick out some bedding for their new 'big bed' is a good way of making it exciting - their favourite story character or colour will make bedtime exciting in their new bed.