The two men have learned a fair bit of trail jargon. TA is for Te Araroa, and a flexitarian is a trail vegetarian who eats meat when staying in a town.
Through walkers do the whole thing in one go. SOBO stands for south-bound - about 90 per cent do start in the north. NOBO means north-bound.
Those people start at Bluff and walk north, arriving in Whanganui in March, April and May. They were a surprise to Firmin and Mills last season, arriving after the SOBO walkers had dried up in January.
NOBO walkers can't canoe up the Whanganui River. They walk the River Rd, get a jetboat from Pipiriki to the Mangapurua Landing, then continue on foot to Whakahoro and National Park.
Most trail walkers are young and from overseas, and some walk for a cause.
Mills and Firmin's first guest, WeeBee, had been an Alaskan park ranger and is one of those people who spend their lives doing long walks. Since doing the TA she has walked several other trails, sending them homemade postcards from all over the world.
A 19-year-old German girl took her time to finish the trail, went home and found returning to normal life difficult.
One very organised young man started the trail the moment he finished school.
Mills and Firmin don't worry about theft as they open their super-organised home and garden to strangers. Firmin said people who set out to walk 3000km carrying a heavy pack tend to be honest.
Whanganui comes at the end of a strenuous week for SOBO walkers. Most have paddled down the Whanganui River from Taumarunui and been without internet access.
In Whanganui they want to rest, resupply, repair equipment and communicate online. Sometimes they stay two nights, and have a rest day. Often they spend $150 to $250 during their time in town.
Firmin and Mills are the only TA hosts here, and they would like Whanganui to be more welcoming. Anyone who wants to be a host can contact them through Facebook, to talk about it.
"It's quite disappointing that our community isn't as aware as it could be," Firmin said.
Trail walkers "hit the wall" at times, and a simple offer of a glass of water or a place to pitch a tent can make their day.
People register online to host the walkers and some hosts ask for a koha. Shops, cafes and approaches to town could put up welcome signs, and shops could offer discounts.
In Northland and Otago people put out boxes of fruit for walkers. In northern Spain, where thousands of pilgrims walk the Camino de Santiago every year, an industry has grown up to supply them.
The route south from Whanganui used to be a black spot on Te Araroa. Last year it was a 28km slog on SH3 and Turakina Beach Rd. It was long, open and dangerous.
Now it leaves Whanganui on Portal St, heads toward Fordell on No 2 Line, veers right down Warrengate Rd, uses 3km of SH3 to cross the Whangaehu River then turns right again, down Whangaehu Beach Rd.
At the beach it heads south down the coast, crossing the Turakina River 500m from the beach at low tide. Markers have just been installed on either side.
Many walkers spend a night at Koitiata's campground, before continuing south along the sand for16km and turning inland toward Bulls.
The 60km from Whanganui to Bulls usually take walkers two days.
Whanganui has a regional Te Araroa Trust with four members: Maureen Bamber, Dave Scoullar, Brian Doughty and Ridgway Lythgoe. The original plan for the route south was to walk the coast from South Beach, with a bridge over the Whangaehu River, and only turn inland near Bulls.
But landowners were unwilling to let walkers cross their land, and the new route is the second fall-back option the trust has tried. It is still hoping for a better long-term solution - perhaps involving that bridge over the Whangaehu River.