Hi, There is another person called 'wellyeknaa' in a similar position, he last posted a couple of weeks ago if you look down 'recent conversations' you could comment to him. His consultant is waiting till he reaches 0.4. There's a better chance of finding something at that level. As you say there is some risk in waiting.
If you wait 6 more months yours is likely to be over 0.5 based on your rate of change if the last 2 were 6 monthly appointments. PSA sometimes increases at different rates. Although you could be on 3 monthly appointments or blood tests.
After your appointment it also depends on how quickly they can scan you, get the results and then another appointment to talk about treatment.
You could ask about these concerns, some people get more worried than others. The above is only what I've read. All the best, Peter