I’m sorry to hear about Freckles, our condolences, but congrats on your new addition!
It’s not so much a certain age we recommend, really once you think you know your pups personality and routine. Certainly wait a few months until your pup is settled in. You can always go back into the surveys and edit you answers if you notice changes (we keep records of the changes, and there are comment sections for each questions).
Also, on her profile you will see “Enroll as Working Dog” she sounds like she will be a great candidate for this part of the research!
Happy to help if you have any other questions about the study, have fun!