To start this DLC hit the touchpad on the controller to bring up the map and then the R1 button (or just right on the d-pad or analogue stick. They all work) over to Extras, press X and you will find the level in there named as "Egghead Eggs-capade".
As usual with all Lego games to open up the free play you must complete the level in story mode first. Once in Free Play you will have access to all those characters you have unlocked to be able to use at will for their abilities that are needed to get all the mini-kits.
Here is a video with all the mini-kits and the Stan Lee in Peril if you still need that. Below it are some lovely time stamps which are also in the video description if you click "show more" under the video on YouTube.
And just for extra ease those lovely time stamps
Minikit 1: 01:05
Minikit 2: 01:29
Minikit 3: 02:23
Minikit 4: 02:42
Minikit 5: 03:16
Minikit 6: 03:43
Stan Lee in Peril: 03:59
Minikit 7: 04:53
Minikit 8: 05:42
Minikit 9: 06:04
Minikit 10: 08:03 09:05 14:37 14:58 15:02
Happy gaming