as the description says, they are not ideal with a Nikko G nib....but they are adequate for your first attempts. if you really love pointed pen work, you will want to invest in a very nice nib holder at some point.
you might want to order one of the Hunt or Gillott nibs. the Gillott 303 is a good beginner nib that will fit your oblique holder. it's not a bad idea to try different nibs. but it is a slippery slope - you can end up with a huge pile of stuff....that you never use. the flip side of the coin, is starting with one nib, never trying anything else and never finding that there are other nibs that might work better for you. down the road, i will have some suggestions...but, i really think your nikko G will be your friend.
H23. Hunt Oblique Penholder
Speedball Oblique Pen holder
Black plastic hourglass shape penholder with offset for nib. For copperplate and Spencerian. The offset helps righthanders with the letter slant. Most lefthanders use a straight holder not this oblique holder. However, some use an oblique holder.
These pointed nibs work in this holder: Hunt 22, Hunt 56, Hunt 99, Hunt 100, Hunt 101, Hunt 103, Hunt 104,
Gillott 170, Gillott 303, Gillott 404, Gillott 1950
Hiro 700, Esterbrook 354, Brause Rose Nib.
The Nikko G nib will work okay, but the holder is not ideal for this nib.