Just seal the whole thing and store it in a dry spot for 6,8 months. Then make your splices.
I've made apple wood bows but never from billets. Mine were staves ,I let them season 2, 5 and I made the last one. It seasoned for 11 years before I built the bow.
I rate apple wood first class bow wood. Seasoned apple wood is hard so it's not a easy wood to work.
But has good speed and cast good. My second bow was read'lly fast and snappy. 62" 57#@26 Use it that buck season. Killed a big doe's missed 2 fox squirrels, missed a red fox I rattled up. Shot over him around 15 yards walking fast. First fox I've ever rattled up and I've did a lottttttttt to rattling.
I only remmeber because it was a dog wood arrow and a very nice TEXAS chert tip. Those two probley took me weeks to make them both.
Since you've cut it down that thin you'd better strap it to a mold. Is this what to mean when you talk about straping it down.
Always let your bow wood season as is. If you do cut it down some to bow form. Have a mold to strap it to. Because any wood cut down that small, let unatented (not straped down) it will warp baddy ,some woods it'll be surver.