Off the top of my head, I don't see any particular security issue linked to the time of voting. I think that's what you mentioned here about family being around. Some obvious points would be not to share the device with the family and to make sure that you use only dedicated hardware and a secure link if you can. However, I don't see any obvious reason why we should worry about a particular time of voting.
Again, I would stress the fact that.... I think if the Chinese want to do something to us, they are not going to do that, try to change your vote from yes to no from time to time, because you will see that right away. No, I would not be too concerned about that.