This is such a common and reoccurring complaint, and has existed since the IPace was first introduced, that is is VERY frustrating that Jaguar hasn't fixed this yet. It really should not be that difficult. We know this because all of us who came over from having a Tesla know that is literally a 10 second procedure in a Tesla. And it works EVERY time (but believe me, even with the issues we all know about, I am very glad to be in the IPace instead of the MS).
The whole charging procedure is needlessly complicated in the IPace, beginning with the fact that the charging functions in the car are NOT to be found under a button called "Charging", but under "Preconditioning". Why not label the button "Charging"??!! I was a fairly early adaptor to the IPace (2019), coming from years with a Tesla, so I was definitely not a novice EV user, and I can't stress enough how frustrating it was trying to figure this issue out. As I said in a Tesla, you just hit the button labeled "Charging", then scroll to "Timed Charging", set the start time and the stop time, and any charging limit that you may want. That is it. And it works flawlessly.
The ONLY fix that works simply and every time with the IPace is with a smart home charger that allows you to set the times within the charger itself and not rely on the car. NO need to remember to jump through all the "preconditioning" time baloney every time you charge your car at home. We should be able to set the times we want, ONE TIME, and just plug in after that. For most EV users this is a fairly important feature because the savings can be pretty substantial with timed charging. For the life of me I cannot figure out why it hasn't been fixed by Jaguar.