You need to get your cows in calf as soon as possible after the planned start of mating and that depends on accurate heat detection.
Cows are able to conceive once every 18-24 days, and lasts on average 14-15 hours but can vary 2-30 hours.
Ovulation happens about 14 hours AFTER the end of standing heat.
Every time you miss an opportunity to put a cow up for AI you have to wait another three weeks, and will therefore miss 3 weeks of milk production. At 1.5MS/cow/day and $7 kg/MS thats about $220 per cow you lose.
Its important to check that the cows have recovered after the birth of their calves and that they have resumed their normal heat cycle.
• use tail paint before planned start of mating
• watch the cows and record activity