This happened to me a while back in the beginning, I’ve been using the extender for almost 3 months now. First 2 weeks is painful, so I used to leave the foreskin covering the glans while getting used to the device, then switch to retracted foreskin since then, it was again, painful but I resorted to using two tricks that still work wonderful for me:
1. Get yourself a soft silicone ring, like the ones used to cover fingers or toes injuries, or some adult toy made of pure silicone in a ring-shaped form that you can cut or adapt. The idea is to have a soft ring to cover the place where the silicone noose will touch your shaft.
2. Get yourself a gauze, like 20cm long would be enough, buy enough so you can replace it after a few days of use, roll it over your dick just behind the glans then put the silicone ring over it, stretching your skin back as much as you can.
3. The silicone noose should be covered also, some extenders come with a soft foam, you could use some gauze also on the noose if needed, so in the end you will end covered in a three-way fashion, gauze, silicone and gauze again.
Using this method I can sit while home office working all day long, some times 8 hours a day, with the usual breaks every 1.5 or 2 hours, and time to go to the bathroom. Always when you feel discomfort, give the guy a break for a couple minutes, massage it if needed, then put the extender back.
For this almost 3 months I’ve gained .6cm EL, and FL looks a lot more hung, like 2cm more in flaccid state. The head I think is growing too, maybe due to the pulling on the glans.
Good luck, and never over do or over stretch beyond comfortable, safety first always.