Mrs Field was prepared for the worse that morning, packing tissues and admitting she almost shed a few tears during the welcoming assembly at The Anglican School, Googong.

"I'm very nervous, I'm terrified," she said.

"I think it's going to be a good school and it's a bit of a smaller school for him to start. It's just what we needed in the area."

It's a particularly hard day for the family as Mrs Field's husband is away serving with the Australian Army in Afghanistan. So, Mrs Field and Conrad, 5, spent the morning documenting the whole experience to later send to husband and make him feel part of the special day.

"My husband left on Boxing Day and we think he'll be gone for a year. It's sad he won't see Conrad's first day but Conrad is proud of him and knows daddy is doing a good job," she said.

"We take lots of pictures and did a video this morning to send to daddy as Conrad was putting his school uniform on. It's just a sacrifice we have to make as a military family. It's sad he's missed the milestone."

Mrs Field said she was finding it hard to let go of Conrad as she has spent everyday with him since she and her husband adopted him from Thailand three years ago.

"We've had Conrad since he was two-years-old. I became a stay at home mum, that's why it's harder for me to let go I think," she said.

"He's been my world and career for the past few years. Entrusting him to other people is a big step for me.

"Conrad was very excited to start school. He woke up about 5am this morning and kept saying 'mummy, it's school today!'.

"He's really excited, it's just me that's sad...I'm letting go of my first baby for the first time."