the distance from the water heater to shower or faucet ,the further the distance ,the more cold water thats in the pipe
water saver devices in both make's it take longer for cold water to be purged from pipes also as opposed to free flow

Any or all of the answers so far. One way to get HW right away is to install a small instantaneous booster heater near or in your bath. It's electric but doesn't run all the time, only when a demand is made for HW. When the HW from the basement comes up, the unit will switch off. You plumber can do this for you.

Distance from the water heater.

New element required in water heater

Cold water in the pipes has to purge first.

Not enough pressure!

Poor water heater

Far away from the water heater.

cold weather