many challenge need a spezial time for download wus most deep in the night is to possible to programm in boinc a timer for download for a spezial konto like pg or or other and start this konto with highes prioriti sorry my english is very bad so please answer in baby englisch or german thanks

You can set specific day-of-the-week overrides for crunching and network communication through the Advanced Local Preferences (see this FAQ for screen shots and explanations of it). If you then set only Primegrid to be crunched, it'll also only download from that project during that time.

These day-of-the-week overrides are only available in the Advanced preferences in BOINC Manager, they aren't available through your web preferences (yet).

Other than that, there's no way that I know of.
It won't increase the priority of crunching...

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