Is the following statement sinful?

My wife is pregnant Alhmadulillah. It's still the beginning of her pregnancy, but I try to buy the baby's things bit by bit to get good offers instead of buying everything last minute. My father told me not to buy so much yet and I answered something like "But at last minute one doesn't have all the money at one time". I know Rizq is from Allah and he could give me as much as he wants any time. What I meant is that I am planning on the grounds of what I have now (monthly). Is that statement and this approach sinful or even kufr? I regret saying it like that.