If you're talking about a few thousand dollars of business per client it's all in the screening: where are they in the process, how do they value the need of the project, when will they move. Those on the fringes are often best avoided even if you lose a few chances as a result. Those who are close need a short sales cycle and into agreement phase... there's no profit in waiting around.
However the further you move up the cost ladder the longer the process, and the less assured the project is. On the extreme end I once had a deal take nearly a year longer to close than intended.
It's not a matter of honesty so much as priority, availability of resources and internal hurtles. Your job as the sales person is both to understand those [so you know where you stand] and to help instill the proper sense of urgency to address them. It's a tough place to be as you rarely know all of the factors on the other side and not everyone is capable of being upfront about their real timelines, if they even know them. Your goal is to find people with the same goal even if they sit across the table so that when things slip, and they will, you're privy as to why.
Thus as much as you may want it to all lay out in a neat circle sometimes you do have to reset expectations and explain that while you're glad to jump when they're ready, you may not be able to jump right away. Those that get it are the clients you want enough to keep leaning on.