Understanding perfume
What does perfume dry down mean
Dry-down is the later character of a perfume as the opening changes and the composition settles in your perception. It describes the developing smell, not simply the moment liquid stops feeling wet.
A HUME Fragrance buying guide

Separate drying from development
A spray can dry while its scent continues changing. When buyers mention loving the dry-down, they usually mean the later fragrance rather than the first impression.
Return instead of smelling constantly
Give a sample space between observations. Note what becomes more noticeable and whether you enjoy the overall impression, rather than trying to detect a change every few seconds.
Use it in the purchase decision
An opening you love may lead to a later scent you do not want to wear. Consider both before buying a bottle, without expecting all perfumes to develop dramatically.
Try this before you buy
Write two descriptions for one sample: first impression and the character you notice later in your normal day.