I last posted about the lilac coloured dress I made for my then 5 month old older grand-daughter - but intended for her in a few weeks' time. Peasant dress for 5 month old girl. I based it on the Stitching Scientist's free pattern. However, there are several other good patterns free on the internet for a similar type of dress, and with tutorials available. The advantage of these is that they may be in different sizes. Stitching Scientist says her pattern was designed to fit one-year old twins who are small for their age, about 6-9 months size. Having tried it, I think it will be fine width wise for my grand-daughter who will be 5-6 months when she wears it, but I had to shorten it.
The one below was made from a different pattern for 0-3 months:
This was also a free pattern for this cute little dress, from Sewmuchado. The 0-3 months size was free when I found it, but she also has patterns in different sizes available to purchase. This web site also has a very clear tutorial (thank you).
This is another free peasant top pattern, from make-your-own-baby-stuff, which comes in several sizes. As the author says, the design is quite forgiving. The elastication round the neck and arms means each size will probably work for at least a few weeks or even months: perhaps first as a long dress, and then as a short top.