First of all, the length of the voyage could vary significantly in pre-modern period depending on the unexpected weather and wind.

AFAIK all the Norse voyages to Vinland or North America in written sources were by way of Norse settlements in Greenland, not went directly through the North Atlantic from Scandinavian Peninsula.

In the saga of Eirik the Red (Chap. 08), It took at least two day's voyage from the Western settlement (around now Nuuk in Western Greenland) to get a view of Helluland (usually identified as Baffin Island), then further two day's voyage to get a sight of Markland, the eastern coast of Labrador Peninsula in now Canada. Then, it is said to take further two days more to get to certain land, what we usually call Vinland (Smiley ed. 2000: 667f.), though I wonder whether these voyage time (ca. 250km per a day) was rather absolute ideal, minimum one thank to the optimum wind and sea current plus 24 hours' sailing (Lungqvist 2005: 27; Thorsteinn Vilhjalmsson 1998).

Some scholars (including myself) now suppose that medieval Greenlanders sometimes went a trip to Markland, i.e. Labrador Peninsula for collecting the good timber resources that was hard to get in Greenlandic settlements, and Ljungqvist allots mainly from June to the end of August for such a navigation, including the work period there to cut tree to timber and so on (Ljungqvist 2005: 16). I personally assume 'around two weeks or a little more (Ljungqvist calculates rowing only in daytime took ca. 4 times more time than optimal sailing) from Greenland' would be on average to sail to Markland, but we don't have any further evidence.

On the other hand, we know certainly a little more about the food during the Viking Age. Please check some of my previous answers in the thread below:

• What did Vikings eat when traveling?
• How did the people of the past dry and store fish and other foods?

Ivar Bardsson also records in his account of Greenland (ca. 1360) that there were some places to catch whales (seals), fishes, and reindeer [caribous?] together with some domesticated animals in or near the Norse settlement in Greenland (Finnur Jónsson utg. 1930, passim).

References:

• Jónsson, Finnur (utg.). Den gamle Grønlands beskrivelse. København, 1930.
• The Sagas of Icelanders: A Selection, with a Preface by Jane Smiley. Harmondsworth: Penguin, 2000.

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• Ljungqvist, Fredrik C. 'The Significance of Remote Resource Regions for Norse Greenland'. Scripta Islandica 56 (2005): 13-54..
• Thorsteinn Vilhjalmsson, 'Old Norse Navigation: An Overview'. In: Aspects of Arctic and Sub-Arctic Society, ed. Ingi Sigurðsson & Jón Skaptason, pp. 364-72. Reykjavík, 2000.

(Added): fixes typos, and fills uncompleted sentences due to failed saving (sorry).