Cooper is expecting strong opposition from the international riders at the remaining rounds at Tokoroa, Pukekohe and Taupo.
"Those guys are all riding well. You can't give them any gap at the start of a moto."
There was BOP success in the 125cc 2-stroke class, the category which showcases the teenage rising stars of the sport.
Te Puke's Logan Blackburn advanced from a mid-pack start in the opening moto to finish fourth and then stepped up with two winning rides on his Yamaha.
With 68 points, Blackburn leads Hamilton's Josiah Natzke - the race one winner - by a single point, while Omokoroa's Aaron Wiltshier (KTM) continued his strong recent form, posting two seconds and a fifth at Timaru and is seven points further back in third place.
"It was good start to the series and I feel like I'm on the right track," said Blackburn, 19, who finished runner-up in the championship last year.
"When I got a bad start in the first race the track was still muddy and one-line. I rode back up to fourth but I had no energy left at the end. The rest of the day went really well."
Mangakino's Kayne Lamont was the first-round MX2 (250cc) winner, going 1-1-2 in the three races to establish a three-point lead over defending champion Scott Columb (Yamaha), of Queenstown, who won race three.
The 37-rider MX2 field provided the biggest mix of results over the first-round action and Australian Jay Wilson (Yamaha) was third.
Rotorua's John Phillips (Honda) and Mount Maunganui's Rhys Carter (Suzuki) were fifth and seventh respectively and Tauranga's Peter Broxholme eighth in the MX2 battle. Carter crashed out in the third race after fourth and fifth places in the earlier races.
Round two of the MX Nationals is at Tokoroa's Amisfield track on February 23.
Backflips NZ Motocross Nationals, Round 1
(Timaru):
MX1 (450cc): 1 Cody Cooper (Papamoa) Honda, 70pts; 2 Ford Dale (Australia) KTM, 67pts; 3 Billy MacKenzie (Scotland) Yamaha, 64pts; 4 Kirk Gibbs (Australia) KTM, 54pts; 5 Brad Groombridge (Taupo) Suzuki, 46pts.
MX2 (250cc): 1 Kayne Lamont (Mangakino) Husqvarna, 72pts; 2 Scott Columb (Queenstown) Yamaha, 69pts; 3 Jay Wilson (Australia) Yamaha, 55pts; 4 Hamish Dobbyn (Auckland) KTM, 51pts; 5 John Phillips (Rotorua) Honda, 47pts.
125cc 2-stroke: 1 Logan Blackburn (Te Puke) Yamaha, 68pts; 2 Josiah Natzke (Hamilton) KTM, 67pts; 3 Aaron Wiltshier (Tauranga) KTM, 60pts; 4 Courtney Duncan (Palmerston) Yamaha, 56pts; 5 Hadleigh Knight (Atiamuri) KTM, 52pts.