Good to put your specs in your signature.

I used to have a PCI card that could make a loop from a standing start. When I switched to firewire I noticed a lag at the start.

So takes time for most cards to get up and running and recording.

I like to use punch in recording and start the transport and when the timeline gets to the start of the measure where the loop marker is then it starts recording and will end at the end of the loop. Actually it will start recording in a loop if you don't stop it. I do single takes this way also.
https://s1manual.presonus.com/Content/R ... ight=punch

You use snap settings to make sure your loop hits on the measures.
https://s1manual.presonus.com/Content/E ... light=snap

Thanks for your answer & the info just edited my signature.

I think there might be some misunderstanding in what I want to do. I want to record within the loopmarker but want that the recording just starts on full beats even if I hit the record button a bit earlier.

So think of the following example. I have a loopmarker of 4 beats and activated playback. Now the playback will always be within these 4 beats. When I now hit the record button a little bit before beat #2 recording starts immediately but I want that it just starts recording exactly on beat #2 ... like playback & recording is timed to beats. In Ableton Live this is possible and is a massive help to concentrate on playing and not on the timing issue to hit the beat exactly.