The pair will fly out for the championships, which start Wednesday, with Horsham athletics coach Ricky Price tomorrow for their events on Friday, Saturday and Sunday.

Bush will contest the girls under-16 90-metre hurdles on Friday, long jump on Saturday and triple jump on Sunday, while Edgerton will contest the boys under-14 javelin on Friday and the four-by-100-metre relay.

Fellow Wimmera athlete Laura Hutchins had also qualified for the nationals in shot put, discus and hammer throw, but chose to withdraw.

Price said he was unsure why Hutchins withdrew, but was still happy to have two Wimmera athletes representing the region.

Bush - a Wimmera Sports Star of the Year nominee in 2013 -  is in good form for the event after an impressive showing at the Little Athletics Victoria Western Country Region track and field championships at the end of February.

She picked up four gold medals and set new Western Region records in triple jump and long jump. The latter was a personal best.

Price said Bush had dealt with an illness and had stopped training for a few days, but was back on track and would be ready for her events.

He said Edgerton was also preparing well for his first national championships.

"In Darcy's last couple of outings he's been below his best, but we did a bit of training on Monday night and sorted a couple of things out," he said.

Price said both had a good chance to do well at the championships.

 "It's Darcy's first time at that sort of competition and it's the first time for all the under-14s, so it's hard to say where he stands with the rest of them," he said.

"I think he's got a chance to get in the top eight - which is the final - if he throws well.

"Hurdles is probably Anna's third event, but last year she finished fourth in that and triple jump, and I reckon she's a good chance to be in the top four in those two again.

"If she jumps around her personal best form, she wouldn't be far off a medal."

The championships will coincide with the Australian Athletics Tour a series of senior track and field competitions showcasing Australia's best talent.

Junior athletes at the championships will get to meet senior champions including Olympic gold medallist Sally Pearson.

Price said it would be a tremendous opportunity for Bush and Edgerton.

"It's a good experience to be up there and compete in that sort of thing, and then to see the seniors will be fantastic," he said.

"Anna missed out on meeting Sally Pearson in Perth last year so she's hoping to do it this year."