Transferring CTF (investment) to Junior Cash ISA

Hi there. Happy New Year to everyone. I am looking for some friendly advice.

After a shock last year when my sons CTF lost about £800, I contacted HSBC to find out more. He is 14 at the end of the month so has 4 years left. They told me that they don't invest any differently towards the 18th birthday so the level of risk remains the same. While the fund has performed really well overall, the last four years have been pretty static and last year- a loss (on that years pay ins, not the overall investment). The latest years statement shows it has recovered and we have made back the loss but based on the last 4 years- if the next 4 went the same- I'd be worried. Although I feel confident it will make an overall profit, there is no guarantee and now seems a good time to withdraw it when it has done well and recovered- cut our losses so to speak and not be greedy with any risk. I am happy with what it has made so far and yes it could continue to grow but it might not and then I'd kick myself if it lost value.

So we've decided to transfer it into a Junior Cash ISA. My question is this. The unit price appears to be calculated on a daily basis at 12 noon. If this fluctuates it can really change the different of the fund value. If I transfer it, I will have no control over when it goes (as the new provider transfers it over) so what it the unit price is particularly bad that day and it goes over on a loss??

Anyone got any experience of this? Is there any way to maximise your fund value?

Thanks in advance.
B