yes, since its the time of the year they lie dormant it would be safe to.

With respect WLB, why would it matter that they're dormant ? I'd personally wait until late spring, just before growth started.

Just my personal view (having looked after a massive tropical palm house and orangery for 5 years)

Lemons want to grow quite big unless they are the miniature ones. Have you decided what you want to do with them eventually? They make nice small standards in tubs - if you wanted to try that with one of them then you would let the leader grow to the height you would want the trunk to be before taking the top out.

Lemon trees are evergreen, so they don't have a period of dormancy, they just slow down during the colder months.

it would matter because if you cut it in the middle of summer you could kill it. after all plants do not appreciate having things cut off of them.
Myron I know they don't stop completely but isn't it what plants are in a state of when its winter?

No, most lemon trees produce fruit all year round. I have a lemon tree that I move into the conservatory during winter. It flowers 4 times a year, so I always have a mixture of flowers, small green pea size lemons all the way up to full size mature lemons on the same tree. It always amuses people when I pick a fresh lemon on Christmas day to serve with Gin and Tonics.

As long as the tree is kept in a reasonably warm place with plenty of light it will grow fruit all year round. Admittedly it does tend to grow better outside during the summer months, but this is due to it receiving more sunlight.

I trim mine mainly during the summer months. It's done four or five times a year. The first trim is done when I first put it out on the patio in spring. I then trim it throughout the summer months with a final trim just before it goes back in the conservatory. I trim it into a ball shape like you would do with buxus.

Thanks all - great info