The most important thing you can do to increase corn yield is to plant early. Even if the soil is not warm enough for fast germination, start planting. The soil will warm up. If you can make a good seedbed do it and get planting.
You have about 100 hours ideally to plant corn without losing yield. There are calculations to indicate that your time is worth about $100.00 per hour during corn planting time. If you have other jobs that you can hire out so that you can keep planting, hire those out. If you can hire someone that you can trust to plant while you cannot plant, hire them.
When working the soil keep it shallow. You want to plant the seed not bury it. Ideally you only need to work a seedbed to a depth of two inches. It is not realistic to work that shallow, but it is realistic to work shallow.
There is no reason to work land much ahead of the planter. You want to plant each day what you work. Should you get rain on land that is worked but not planted, this land will take longer to dry than land that has not been worked. Many growers will not start planting until all the manure is out. This can be a mistake. Planters should start as soon as the soil is fit. Consider planting corn even before all the manure is out. Generally if it is too wet to plant it is too wet to spread manure without causing compaction that can decrease yields.
Weather predictions during the spring season in southern Ontario are very unreliable. If the weather is good for planting now but they are predicting good weather for tomorrow don’t believe them. Keep on planting. Weather systems that come up the Ohio Valley into Ontario are very unpredictable. Sometimes they bring what they should and other times the system breaks up before they get across the Great Lakes. Finally, take time to be safe. BF