You can spend your money immediately but are you spending it on something worth its price? Something valuable? Something that is necessary?
I think all of this doesn't really matter whether you spend your money slow or fast, what really matter is the ability for you to spend your money wisely basically on things that matters most cause that not withstanding that money would be spent. And another thing is being able to discipline yourself financially cause most times you tend to spend the money on reasonable things but once the money comes it's been diverted to something else.
When it comes to money, what's more important than spending wisely is a higher income. Because when our income increases beyond our normal limits, we can naturally find wise ways to use our money ourselves through various methods, one of which is what you mentioned. Because when it comes to the speed or slowness of our desired growth, it still depends heavily on our level of hard work and intelligence in generating money using the knowledge we already possess. So, wise use of money must also be accompanied by a wiser income level so that growth in our lives can be faster and better.