You can do the incremental load as follows :-
a) Extract the last run date from the DB and store in context variable. Also store the current time in another context variable.
b) Execute the SQL query from source database to extract the incremental data. Make sure your query's where clause is having both last run date and current system date stored in context variables.
c) Once the data extraction is complete, load the new system date from context variable to configuration table storing last run dates.
Another approach to extract the delta data is to implement the CDC (Change Data Capture) in source tables. Below link can give details about Talend CDC capabilities.
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