令人一頭霧水的綠卡問題><（i-140 & i-485) - 海外工作

我目前的情況：
顧主：州立大學
職位：assistant professor
visa：H1b三年效期剛過，延簽正在辦理中（已於上個月拿到Form I-797，
相關文件上寫的是「240 day employment authorization extension」，
我也不太清楚為什麼是240天...）

綠卡辦理狀況：PERM剛過，剛要開始辦I-140

律師來信問我要選擇哪一種做法:
1. File your application for adjustment of status (green card) simultaneously
with the I-140 petition.
2. File the I-140 petition as premium and then file the adjustment
application once the I-140 is approved.

As of today, your priority
date is current through September 30, 2013. We will know mid-September
if it will remain current for October.

我大概知道這兩者一起辦的風險在於
一但公司財物不夠穩定或其他原因導致i-140沒過，我也就失去H1B的保護傘。
不過以州立大學而言，這點好像又不太可能發生。

律師表示
We can always submit the I-140 as regular and then if you wanted to
upgrade you can do that at a later date (we charge an administrative
fee of $100 to process the upgrade request at a later date)

這麼說起來，以目前狀況是否是同時file i-140 和 i-485 比較理想呢？

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