Rafi Magid asked:
1. According to the opinion that OLOT wewe before matan torah - why didn't the gemara prove that from akeidat izthak ("VAYAA'LE'HU LEOLA'H TAHAT BNO")?
2. What did they do after 5 at Sivan till 1 at Nisan the next year when the Mishkan was established?
The Kollel replies:
1) There were Olos before the Akeidah also. Kayin and Hevel brought Olos, as did Noach. The question is whether the Mitzvah given to B'nei Yisrael of Korban Olas Re'iyah predates Matan Torah, which would then be a Chumra. That is only if the Korban brought at Sinai was an Olas Re'iyah.
2) Although I did not find this explicitly, it seems that according to all those who hold that they brought a Tamid at Sinai they continued to bring it on a Bamah until they built the Mishkan.
D. Zupnik