You'll still need a permit to dayhike, or overnight between the portal and the summit.
The lottery started back in February so you may need to call the local ranger station and find out how many permits may be available on the dates you want. If it is during the week, you may be more lucky than a weekend. Especially if you're planning it over Labor day weekend.
for more info.
As of right now, it looks like your chances of overnighting above the portal are slim unless you are lucky enough to pick up a permit the day before at the ranger station (occasionally they have permits that go unclaimed the day before).