The size and nature of the universe just before cosmic inflation commenced are still subjects of active research and scientific investigation. Our current understanding of the early universe is based on theoretical models and observational evidence, but there are aspects that remain uncertain.
According to the prevailing inflationary cosmology theory, cosmic inflation is a period of rapid expansion that occurred in the very early universe, shortly after the Big Bang. It is hypothesized to explain several observed characteristics of the universe, such as its overall homogeneity, isotropy, and the origin of the cosmic microwave background radiation.
During cosmic inflation, the universe underwent an exponential expansion, which caused it to increase in size by an enormous factor. However, the precise size of the universe just before inflation and whether it was finite or infinite is not well-defined in the current scientific understanding. Inflation is believed to have smoothed out irregularities and expanded the universe to a significantly larger scale, but the exact nature of its initial conditions and the pre-inflationary universe remain areas of ongoing research.
As for the concept of the universe being infinite now, it is important to note that the question of the size and nature of the universe on a global scale is still an open topic of investigation. While the observable universe appears to be finite due to the finite speed of light and our ability to observe only a limited portion, the question of whether the entire universe is infinite or finite is a matter of debate and exploration in cosmology.