I use the small animal nail clippers, the ones that look like scissors. Whilst they are still so young they do not need their nails doing immediately. However, their nails are likely needle sharp so you could potentially take off the very, very tip of the nail (1mm) so that the nail is more blunt.
My 5 month old still has very little nails still, so I am not cutting his nails for a little while yet, their nails don't tend to grow thick or curly whilst they are still little. Tia, who is about 20 months old has longer nails but still only need about a couple of mm taken off at a time as any more I risk catching the quick.