Every single time you're with a prospect, you need to close for something (not always an order). For example, when they tell you "... maybe in August...", you need to understand why August and not now. So, you might try, "... just to make sure I understand you, what will happen between now and August?".
If the answer doesn't make sense, ask questions which will help you understand.
YOU NEED TO WORK THIS TOPIC INTO THE DIALOGUE: Make sure you fully understand the relationship with the main supplier(s): they might be relatives! If it's not family, ask the question, "... when you originally started dealing with them, what specific criteria made you select them over competitors?" and, "... now that you've been working with them for a period of time, what improvements would you appreciate seeing?"
Have them assign priority to the list of criteria in selecting "the perfect supplier". When pushed into this mode, I frame the question like this, "... if I handed you the canvas and pallet and asked you to paint me a picture of the perfect supplier, what would it look like?" Seems abstract but you'd be surprised how it brings things into focus.
Never let a prospect think that "persistence" is bad: "Wouldn't you prefer that all of your SRs were working their prospects in a similar fashion?".
Not all of your suspects will turn into prospects into customers! But you need to remember that there is a time dynamic in sales, so, today's suspects are tomorrow's customers! Never leave without advancing the sales cycle ...
Good luck & Good selling!
Pat