Can anyone help me with emile et rose sizing?

[notso]

I have seen a lovely romper for DS2 to wear for his Christening but not sure of size to order. I don't want to leave it too long as it's in the sale.
He was 13lb 4oz last week and is either wearing 0-3 month or 3-6 month clothes depending on the make.
The Christening is in about a month he'll be 13 weeks then.
TIA

We've only had one E&R dress, but IIRC that was pretty standard-sized. I'd go for the 3-6 month size in your place.

Thanks Prof, managed to find both sizes cheaper on good old Ebay.