Hello @utajhya and welcome to the KNIME forum
Aiming to provide some advise to your challenge, would be better if you can provide a sample of your data problem or a dummy analogue. Then, people in forum will be predisposed to collaborate by having some data to work with.
And trying to offer you some brainstorming about your use case; I think a first step for your analysis would be to align the data (monthly granularity) to the first gift by donor. This alignment -months from first gift- (M0, M1…) will give you the right reference axis to start your plotting, fit, regressions…
This workflow elaborated for a past forum discussion, and despite the time granularity is based in years; it can give you some insights for the data preparation.
BR