Use a tdee calculator like https://tdeecalculator.net and aim to eat under your resting/maintenance number.
Without knowing your stats, it’s hard to say if 1000 calories is enough. For most people, it’s not. 1200 calories is usually considered the minimum we’d recommend. (Unless you’re petite - under 5’4”)
One big meal is the best by far. A ‘gold standard’ of sorts.
The meal should be of a size that feels right, in terms of satiation. It should not feel restrictive. If you restrict the meal, you will typically end up in the trap of down-regulated metabolic rate.