"There's been a lot of information to take on board. It's been a bit overwhelming, all the stuff I've had to get my head around over the past couple of weeks. But I've had a lot of help and support and I definitely feel ready," the Porirua-born star said.
"I'm not sure what to expect. I think for me, it's kind of about embracing this moment and being part of the Silver Ferns environment - that in itself is such a huge thing - but to be able to play will be another big step and even cooler, so I guess I'll just wait and see what happens."
While a decision was yet to be made yesterday on whether Souness would get her opportunity to debut this weekend, Southby said she has been impressed with how the young midcourter has taken the added demands of the national team in her stride and is stepping up on court.
"She's certainly put her hand up in camp. She's energetic, she brings a lot of variety into our attacking game and I've been impressed with what she's been putting out there."
Southby said given the change the Ferns have already been through in the past 12 months, she is mindful of the need to keep developing connections in the top combinations and will not be throwing players on "willy-nilly". But the need to develop depth in the squad is also acute.
Ferns management have selected two different line-ups for the Quad Series and three-test series against England next month. Souness, fellow midcourter Sam Sinclair, shooter Maia Wilson and athletic defender Phoenix Karaka will be swapped out for the English series in favour of Grace Rasmussen, Kayla Cullen, who is returning from minor knee surgery, Monica Falkner and Temalisi Fakahokotau respectively.
The Quad Series starts tonight with Australia taking on England, before the Ferns play South Africa at the same Brisbane venue.
Netball Quad Series
Today, Brisbane Entertainment Centre
5pm: Australia v England
7pm: New Zealand v South Africa