Delay when powering LED light strip
The more 'electronic' a power supply, the longer it takes to start up.  I had this nuisance in my pantry, where I only need light for a few seconds, so I don't want to wait another few seconds every time.  I also have a VERY high current demand from a lot of LEDs in total.

I used a sealed lead acid battery on a trickle charger, and a relays.  Battery is on common.  NO is connected to LEDs.  NC to a trickle charger.

Yeah.  I'll have to replace the battery when it goes out.  Beats waiting for a power supply to ramp up.

Long term, I think I'm going to make a service grade (100-400A) 12/24/48v DC bus for the house, with capacitors for buffering.

You might try a very simple 120vAC to 12vAC transformer (assuming thats your LED's voltage) with a rectifier and capacitor in some enclosure.  You're building electrics at that point, so test, and include fuses, etc.