Depends on what you are feeding, I think.
Starter crumble is recommended by Storey's Guide for the first 2 or 3 weeks. Then slowly (by combining them) switch over to grower/maintenance.
However, there are some different formulations. Can you tell us what you are feeding now?
I would start adding in a good grower/maintenance feed soon. Do you know what is available for you? I am not an expert on all the available feeds. But perhaps others can check in.
I have used Blue Seal organic, and Purina (way back, if I recall), and now use Countryside Organic with the occasional Mazuri Breeder.