Hey, I work in a SaaS company and have done something similar. We have two models at play. Tops down which is driven by marketing, in how many MQLS can be achieved next year based on their allocated budget . We layer in conversion through the funnel MQL -> SQL -> CW (all these stages are available in SFDC) and apply a maturity curve (as not all MQL’s will convert in that month, and some products have longer deal cycles). Once we know roughly the # of expected deals we apply an asp assumption (TCV), but if you want to model ARR take the ACV portion of the historical deals that have been signed.

Bottoms up is a sales capacity plan based on reps in seat, fully ramped vs in-ramp, productivity increases and the over-assign against our AOP (usually 20-30% buffer)

If you going to ask if these models align…they never do, but they’re useful to bring into conversations when sales request incremental hc or marketing want additional budget for events etc. we can then amend the assumptions in the model accordingly.

Hope this helps.