It depends what you mean by bills. Are you talking about just your rent and utilities, or are you including gas, car insurance, phone, food, etc.? If your entire cost of living was only $500 a month, then I would say you should be saving somewhere around $1000 a month. There's no way you should need more than $200 a month for variable expenses and spending money. However I'm assuming that the $500 is kind of a rough number based on a few of your major expenses. You need to write down all of your expenses on paper and then decide what are fixed expenses (things that you need in order to live like rent, transportation, food) and then eliminate the non-essentials if you want to save more. You should be able to live on about 80% of your take home income. That way you put about 20% away into savings, investments, etc.
Wait until the end of the month to put money in savings. That way you will know for sure how much you have left over.
If you're able to save 20% you're doing well. 20% of $1700 is only $240. You should be able to put away at least $500, considering your total monthly expenses are only $500.
I'd be putting at least $800 in, that leaves money to pay your bills +$400 extra so you don't end up "broke"
