Soak the firing 30 minutes to mature the mug and the planter will not mature. Soak 2 hours for the planter and the glaze may melt too much and the clay be too vitreous. This is a troublesome issue with electric kilns. Furthermore, they employ radiant heat. That means that sections of ware on the shady side (or the under side) will never reach the temperature of those on the element side no matter how long you soak.
Electric Hobby Kilns: What You Need to Know
Electric hobby kilns are certainly not up to the quality and capability of small industrial electric kilns, but if you are aware of the limitations and take precautions they are workable.
The process of holding a kiln at the final temperature (or at other temperatures) to enable the heat to penetrate the ware or to effect or complete a glaze or body reaction
A term used in the ceramics industry to signify the degree of vitrification in a fired clay. Mature clays are dense and strong, immature ones porous and weak.