General Question on how DTP works

Scenario in 3.5 (old dataflow): A datasource loading data to an ODS via a infopackage (Delta).

Scenario in BI 7 (new dataflow): Created a transformation and DTP (completely migrated to BI7). Now the data has to be loaded first to the PSA (using the old infopackage) and then run DTP (Delta) to load the DSO.

Suppose the old data flow (which is in 3.5) in alreay in Production and it is up and running daily (Delta loads from R/3). Now when the dataflow is migrated to BI 7 in Development and transported to Production, when I run the infopackage (which is still delta) loads new delta records to the PSA only. So my question is when I run the DTP for the first time, Does it try to load all the data that is in PSA or just the lastest delta load happened?