Well now that depends. Are you planning on moving the cattle daily? or just put them out there and leave them?
If you are moving you cattle you will get double or triple the production
Spring grass will always have a low Leaf area index (L.A.I.) so move them often.
Do not put cattle on spring grass until it has growth of at least eight inches at this point the L.A.I. is still low so move the animals quickly and let the area recover more before regrazing. A good rule of thumb is not to put cattle on a plot until there are at least three or four leaves on each grass plant.
When you see shaded areas in your field you have 65 to 70% interception of solar energy
Stay in phase 2 for best management, grazing at twelve inches down to no less than 4 inches (the bottom size of phase 2) and never graze to phase 1. A good rule of thumb is graze ½ leave ½. Grazing to phase 1 will add 15 days to the regrowth period and you will lose 30% of pasture productivity.
The size your paddocks will determine on how long it will take for animals to graze it down to that level however if you leave the cattle on a paddock too long they start to graze the new growth which will stunt the plants root and its ability to regrow. Because of this it's best to move cattle every day and never leave them on a paddock for more than three days. Operating in a pasture that is using a 60% solar utilization rate is twice as productive as a pasture in a 30% utilization rate. (twice as much food is produced!)