Since you don't have enough knowledge about investing in Bitcoin, do enough research and gather a lot of knowledge about investing before you invest. Everything you need to know about your investment. And before investing first prepare yourself for full investment. If you get a salary of $300 per month, if you invest $50 in bitcoins out of that, you can very well serve your family and all your personal expenses with $250. You don't need any exact time to buy bitcoins, if you invest in long term you will definitely get profit. Just invest for long term. If you continue to invest in Bitcoin in this way, you will surely achieve great success in life.
And good luck to you