I conducted a study where the participant had to decide between a sooner smaller and a delayed larger reward option. Across the experiment the delayed larger reward option stayed the same while the sooner smaller was adjusted per trial depending on the choice the subject made
That means that I collected all the adjusted sooner monetary reward options getting adjusted across 7 trials. I ran these 7 trials 30 times involving different time points
It's not exactly clear from your question but it sounds like your design is not incentive compatible. In other words the subjects could manipulate the choices they saw later in the experiment via the answers they gave earlier in the experiment. Leaving that aside, a classic reference is http://www.jstor.org/stable/3083267 - Estimating Individual Discount Rates in Denmark: A Field Experiment, Glenn W. Harrison, Morten I. Lau and Melonie B. Williams