Early stage companies thrive on the speed of idea generation and prototyping. You start with a reasonably good idea, test the market, iterate on the idea to make it a great one, and deliver on the first stage of the product.
At this point you've got your first sellable merchandise. You also have another wheelbarrow full of additional ideas where you can take the product based on customer feedback and the natural evolution of the original idea. It is tempting to keep selling the dream. Unless the first incarnation of your product is ill received it is important to sell that concrete thing which you have just completed building. Now it may have a few warts and one of the arms isn't quite fully developed, that's OK. Sell what you have and co-opt your customers into helping you define the next stage of the product.
If you are continually selling the dream (or the next generation of the product) your trial periods will extend indefinitely. This will result in much slower revenue (and revenue recognition) and effectively shorten your runway. So do not short change yourself. Sell what you have today, execute to over deliver what you've sold, and your happy customer will help you refine and pay for your ideas of tomorrow.